Dramatic improvements in survival have been achieved for children and adolescents with cancer. Between 1975 and 2020, childhood cancer mortality decreased by more than 50%.[1-3] Childhood and adolescent cancer survivors require close monitoring because cancer therapy side effects may persist or develop months or years after treatment. For information about the incidence, type, and monitoring of late effects in childhood and adolescent cancer survivors, see Late Effects of Treatment for Childhood Cancer.
Pediatric soft tissue sarcomas are a heterogenous group of malignant tumors that originate from primitive mesenchymal tissue and account for 6% of all childhood tumors (rhabdomyosarcomas, 3%; other soft tissue sarcomas, 3%).[2] For more information, see the Histopathological Classification of Childhood Soft Tissue Sarcoma section.
Rhabdomyosarcoma, a tumor of striated muscle, is the most common soft tissue sarcoma in children. It accounts for 50% of the soft tissue sarcomas in children aged 0 to 14 years.[2] For more information, see Childhood Rhabdomyosarcoma Treatment.
In pediatrics, the remaining soft tissue sarcomas are commonly referred to as nonrhabdomyosarcomatous soft tissue sarcomas (NRSTS) and account for approximately 3.5% of all childhood tumors.[2,4] This summary discusses the treatment of NRSTS.
NRSTS are often classified according to the normal tissue types from which they are derived. These types include various connective tissues, peripheral nervous system tissue, smooth muscle tissue, and vascular tissue. The classification also includes undifferentiated tumors that are not clearly related to specific tissue types. For more information about vascular tumors in children, see Childhood Vascular Tumors Treatment.
The distribution of soft tissue sarcomas by histology and age, on the basis of the Surveillance, Epidemiology, and End Results (SEER) Program information from 2000 to 2015, is depicted in Table 1. The distribution of histological subtypes by age is also shown in Figure 2.
Age <5 y | Age 5–9 y | Age 10–14 y | Age 15–19 y | Age <20 y | All Ages (Including Adults) | |||
---|---|---|---|---|---|---|---|---|
pPNET = peripheral primitive neuroectodermal tumors; SEER = Surveillance, Epidemiology, and End Results. | ||||||||
aSource: SEER database.[5] | ||||||||
All soft tissue and other extraosseous sarcomas | 1,124 | 773 | 1,201 | 1,558 | 4,656 | 80,269 | ||
Rhabdomyosarcomas | 668 | 417 | 382 | 327 | 1,794 | 3,284 | ||
Fibrosarcomas, peripheral nerve, and other fibrous neoplasms | 137 | 64 | 112 | 181 | 494 | 6,645 | ||
Fibroblastic and myofibroblastic tumors | 114 | 33 | 41 | 77 | 265 | 4,228 | ||
Nerve sheath tumors | 23 | 31 | 70 | 102 | 226 | 2,303 | ||
Other fibromatous neoplasms | 0 | 0 | 1 | 2 | 3 | 114 | ||
Kaposi sarcoma | 2 | 1 | 2 | 10 | 15 | 7,722 | ||
Other specified soft tissue sarcomas | 237 | 238 | 559 | 865 | 1,899 | 49,004 | ||
Ewing tumor and Askin tumor of soft tissue | 37 | 36 | 72 | 113 | 258 | 596 | ||
pPNET of soft tissue | 24 | 23 | 42 | 56 | 145 | 402 | ||
Extrarenal rhabdoid tumor | 75 | 8 | 9 | 4 | 96 | 205 | ||
Liposarcomas | 4 | 6 | 37 | 79 | 126 | 10,749 | ||
Fibrohistiocytic tumors | 43 | 73 | 142 | 223 | 481 | 13,531 | ||
Leiomyosarcomas | 11 | 14 | 19 | 41 | 85 | 14,107 | ||
Synovial sarcomas | 12 | 39 | 141 | 210 | 402 | 2,608 | ||
Blood vessel tumors | 12 | 9 | 11 | 32 | 64 | 4,238 | ||
Osseous and chondromatous neoplasms of soft tissue | 1 | 6 | 16 | 14 | 37 | 1,018 | ||
Alveolar soft parts sarcoma | 4 | 5 | 22 | 33 | 64 | 211 | ||
Miscellaneous soft tissue sarcomas | 14 | 19 | 48 | 60 | 141 | 1,339 | ||
Unspecified soft tissue sarcomas | 80 | 53 | 146 | 175 | 454 | 13,614 |
NRSTS are more common in adolescents and adults.[6] Most of the information regarding treatment and natural history of the disease in younger patients has been based on studies in adult patients. The distributions of these tumors by age according to stage (Figure 1), histological subtype (Figure 2), and tumor site (Figure 3) are shown below.[7]
Some genetic factors and external exposures have been associated with the development of NRSTS, including the following:
NRSTS can develop in any part of the body, but they arise most commonly in the trunk and extremities.[28-30] Although rare, these tumors can arise in brain tissue and are treated according to the histological type.[31]
NRSTS can present initially as an asymptomatic solid mass, or they may be symptomatic because of local invasion of adjacent anatomical structures. Systemic symptoms (e.g., fever, weight loss, and night sweats) are rare. Hypoglycemia and hypophosphatemic rickets have been reported in cases of hemangiopericytoma (now identified as a solitary fibrous tumor in the revised World Health Organization classification system), whereas hyperglycemia has been noted in patients with fibrosarcoma of the lung.[32]
When a suspicious lesion is identified, it is crucial that a complete workup, followed by adequate biopsy be performed. The lesion is imaged before initiating any intervention using the following procedures:
The imaging characteristics of some tumors can be highly suggestive of that particular diagnosis. For example, the imaging characteristics of pediatric low-grade fibromyxoid sarcoma and alveolar soft part sarcoma have been described and can aid in the diagnosis of these rare neoplasms.[36]
Although NRSTS are pathologically distinct from rhabdomyosarcoma and Ewing sarcoma, the classification of childhood NRSTS type is often difficult. Core-needle biopsy, incisional biopsy, or excisional biopsy can be used to diagnose NRSTS. If possible, the surgeon who will perform the definitive resection needs to be involved in the biopsy decision. Poorly placed incisional or needle biopsies may adversely affect the ability to achieve negative margins.
Needle biopsy techniques must ensure adequate tissue sampling. Given the diagnostic importance of translocations and other molecular changes, a core-needle biopsy or small incisional biopsy that obtains adequate tumor tissue is crucial to allow for conventional histological and immunocytochemical analysis and other studies such as light and electron microscopy, cytogenetics, fluorescence in situ hybridization, and molecular pathology.[37,38]
The acquisition of multiple cores of tissue may be required. Of 530 suspected soft tissue masses in (largely adult) patients who underwent core-needle biopsies, 426 (80%) were proven to be soft tissue tumors, 225 (52.8%) of which were malignant. Core-needle biopsy was able to differentiate soft tissue sarcomas from benign lesions with a sensitivity of 96.3% and a specificity of 99.4%. Tumor subtype was accurately assigned in 89.5% of benign lesions and in 88% of soft tissue sarcomas. The biopsy complication rate was 0.4%.[39]
Considerations related to a biopsy procedure are as follows:
In a prospective study of pediatric patients with sarcoma who underwent sentinel lymph node biopsy, 28 patients were examined. Sentinel lymph node biopsy was positive in 7 of the 28 patients, including 3 patients (43%) who had negative PET-CT scans. PET-CT overestimated and suggested nodal involvement in 14 patients, more than what was confirmed by sentinel lymph node biopsy. The findings from the sentinel lymph node biopsies resulted in altering therapy for all seven patients who were determined to have metastatic disease. As indicated by previous reports, epithelioid sarcoma and clear cell sarcoma were the two NRSTS included in this study.[50]
Transverse extremity incisions are avoided to reduce skin loss at re-excision and because they require a greater cross-sectional volume of tissue to be covered in the radiation field. Other extensive surgical procedures are also avoided before definitive diagnosis.
For these reasons, open biopsy or multiple core-needle biopsies are strongly encouraged so that adequate tumor tissue can be obtained to allow crucial studies to be performed and to avoid limiting future treatment options.
In children with unplanned resection of NRSTS, primary re-excision is frequently recommended because many patients will have tumor present in the re-excision specimen.[52,53] A single-institution analysis of adolescents and adults compared patients with unplanned excision of soft tissue sarcoma to stage-matched controls. In this retrospective analysis, unplanned initial excision of soft tissue sarcoma resulted in increased risk of local recurrence, metastasis, and death. This increased risk was greatest for high-grade tumors.[54][Level of evidence C1] In this case, a second resection is expected.
Many NRSTS are characterized by chromosomal abnormalities. Some of these chromosomal translocations lead to a fusion of two disparate genes. The resulting fusion transcript can be readily detected by using polymerase chain reaction–based techniques, thus facilitating the diagnosis of those neoplasms that have translocations.
Some of the most frequent aberrations seen in NRSTS are listed in Table 2.
Histology | Chromosomal Aberrations | Genes Involved |
---|---|---|
aAdapted from Sandberg,[55] Slater et al.,[56] Mertens et al.,[57] Romeo,[58] and Schaefer et al.[59] | ||
Alveolar soft part sarcoma | t(x;17)(p11.2;q25) | ASPSCR1::TFE3 [60-62] |
Angiomatoid fibrous histiocytoma | t(12;16)(q13;p11), t(2;22)(q33;q12), t(12;22)(q13;q12) | FUS::ATF1, EWSR1::CREB1,[63] EWSR1::ATF1 |
BCOR-rearranged sarcomas | inv(X)(p11.4;p11.2) | BCOR::CCNB3 |
CIC-rearranged sarcomas | t(4;19)(q35;q13), t(10;19)(q26;q13) | CIC::DUX4 |
Clear cell sarcoma | t(12;22)(q13;q12), t(2;22)(q33;q12) | EWSR::ATF1, EWSR1::CREB1 [64] |
Congenital (infantile) fibrosarcoma/mesoblastic nephroma | t(12;15)(p13;q25) | ETV6::NTRK3 |
Dermatofibrosarcoma protuberans | t(17;22)(q22;q13) | COL1A1::PDGFB |
Desmoid fibromatosis | Trisomy 8 or 20, loss of 5q21 | CTNNB1 or APC variants |
Desmoplastic small round cell tumors | t(11;22)(p13;q12) | EWSR1::WT1 [65,66] |
Epithelioid hemangioendothelioma | t(1;3)(p36;q25) [67] | WWTR1::CAMTA1 |
Epithelioid sarcoma | Inactivation of SMARCB1 | SMARCB1 |
Extraskeletal myxoid chondrosarcoma | t(9;22)(q22;q12), t(9;17)(q22;q11), t(9;15)(q22;q21), t(3;9)(q11;q22) | EWSR1::NR4A3, TAF2N::NR4A3, TCF12::NR4A3, TFG::NR4A3 |
Hemangiopericytoma | t(12;19)(q13;q13.3) and t(13;22)(q22;q13.3) | LMNA::NTRK1 [68] |
Infantile fibrosarcoma | t(12;15)(p13;q25) | ETV6::NTRK3 |
Inflammatory myofibroblastic tumor | t(1;2)(q23;q23), t(2;19)(q23;q13), t(2;17)(q23;q23), t(2;2)(p23;q13), t(2;11)(p23;p15) [69] | TPM3::ALK, TPM4::ALK, CLTC::ALK, RANBP2::ALK, CARS1::ALK, RAS |
Infantile myofibromatosis | Gain-of-function variants | PDGFRB [70] |
Low-grade fibromyxoid sarcoma | t(7;16)(q33;p11), t(11;16)(p11;p11) | FUS::CREB3L2, FUS::CREB3L1 |
Malignant peripheral nerve sheath tumor | 17q11.2, loss or rearrangement of 10p, 11q, 17q, 22q | NF1 |
Mesenchymal chondrosarcoma | Del(8)(q13.3q21.1) | HEY1::NCOA2 |
Myoepithelioma | t(19;22)(q13;q12), t(1;22)(q23;q12), t(6;22)(p21;q12) | EWSR1::ZNF44, EWSR1::PBX1, EWSR1::POU5F1 |
Myxoid/round cell liposarcoma | t(12;16)(q13;p11), t(12;22)(q13;q12) | FUS::DDIT3, EWSR1::DDIT3 |
Primitive myxoid mesenchymal tumor of infancy | Internal tandem duplication | BCOR |
Rhabdoid tumor | Inactivation of SMARCB1 | SMARCB1 |
Sclerosing epithelioid fibrosarcoma | t(11;22)(p11;q12), t(19;22)(p13;q12) | EWSR1::CREB3L1, EWSR1::CREB3L3 |
Solitary fibrous tumor | inv(12)(q13q13) | NAB2::STAT6 |
Synovial sarcoma | t(x;18)(p11.2;q11.2) | SS18::SSX |
Tenosynovial giant cell tumor | t(1;2)(p13;q35) | COL6A3::CSF1 |
The prognosis of NRSTS varies greatly depending on the following factors:[71-73]
In a review of a large adult series of NRSTS, patients with superficial extremity sarcomas had a better prognosis than did patients with deep tumors. Thus, in addition to grade and size, the depth of invasion of the tumor should be considered.[74]
Several adult and pediatric series have shown that patients with large or invasive tumors have a significantly worse prognosis than do those with small, noninvasive tumors. A retrospective review of soft tissue sarcomas in children and adolescents suggests that the 5 cm cutoff used for adults with soft tissue sarcoma may not be ideal for smaller children, especially infants. The review identified an interaction between tumor diameter and body surface area.[75] This relationship has been questioned and requires further study to determine the therapeutic implications of the observation.[76]
Some pediatric NRSTS are associated with a better outcome. For instance, patients with infantile fibrosarcoma who present at age 4 years or younger have an excellent prognosis. This excellent outcome occurs because surgery alone can cure a significant number of these patients and infantile fibrosarcoma is highly chemosensitive. This tumor also responds well to larotrectinib, a specific tropomyosin receptor kinase inhibitor.[22,77]
Soft tissue sarcomas in older children and adolescents often behave similarly to those in adult patients.[22,78] A large, prospective, multinational COG study (ARST0332 [NCT00346164]) enrolled newly diagnosed patients younger than 30 years. Patients were assigned to treatment on the basis of their risk group. Risk groups were defined by the presence of metastasis, tumor resectability and margins, and tumor size and grade. For more information, see Figure 4.[79][Level of evidence B4]
Each patient was assigned to one of three risk groups and one of four treatment groups. The risk groups were as follows:[79]
The treatment groups were as follows:
Chemotherapy included six cycles of ifosfamide (3 g/m2 per dose) administered intravenously on days 1 through 3 and five cycles of doxorubicin (37.5 mg/m2 per dose) administered intravenously on days 1 to 2 every 3 weeks, with the sequence adjusted on the basis of the timing of surgery or radiation therapy.
For the 550 patients enrolled, 529 evaluable patients were included in the analysis; at a median follow-up of 6.5 years (interquartile range [IQR], 4.9–7.9), the survival results are shown in Table 3.
5-Year Event-Free Survival | 5-Year Overall Survival | |||
---|---|---|---|---|
Risk Group | Events/Patients | Estimate, % (95% CI) | Events/Patients | Estimate, % (95% CI) |
CI = confidence interval; R0 = completely excised with negative microscopic margins; R1 = grossly excised but with positive microscopic margins; R2 = less than complete gross excision. | ||||
Low | 26/222 | 88.9 (84.0–93.8) | 10/222 | 96.2 (93.2–99.2) |
Intermediate | 84/227 | 65.0 (58.2–71.8) | 55/227 | 79.2 (73.4–85.0) |
High | 63/80 | 21.2 (11.4–31.1) | 52/80 | 35.5 (23.6–47.4) |
Surgical Margin | ||||
R0 | 44/252 | 83.6 (78.3–89.0) | 22/252 | 92.8 (89.1–96.5) |
R1 | 29/81 | 66.2 (54.8–77.5) | 17/81 | 79.7 (70.0–89.5) |
R2 | 100/196 | 49.2 (41.4–57.0) | 78/196 | 62.7 (55.2–70.3) |
Pediatric patients with unresected localized NRSTS have a poor outcome. Only about one-third of patients treated with multimodality therapy remain disease free.[71,80]; [81,82][Level of evidence C1] In an Italian review of 30 patients with NRSTS at visceral sites, only ten patients survived at 5 years. Unfavorable prognostic factors included inability to achieve complete resection, large tumor size, tumor invasion, histological subtype, and lung-pleura sites.[83][Level of evidence C1]
The EpSSG conducted a prospective trial for patients younger than 21 years with NRSTS. They reported an analysis of 206 patients with synovial sarcoma and 363 with adult-type NRSTS. Patients were treated according to assigned risk groups. For more information, see Figure 5.[84] With a median follow-up of 80 months (interquartile range, 54.3–111.3) for the 467 surviving patients, the 5-year event-free survival (EFS) rate was 73.7% (95% CI, 69.7%–77.2%), and the OS rate was 83.8% (95% CI, 80.3%–86.7%). The survival by treatment groups are shown in Table 4.[84]
Treatment Group | 5-Year Event-Free Survival Rate (95% CI) | 5-Year Overall Survival Rate (95% CI) | Local Recurrence Rate |
---|---|---|---|
CI = confidence interval; EpSSG = European paediatric Soft Tissue Sarcoma Study Group; NRSTS = nonrhabdomyosarcomatous soft tissue sarcomas. | |||
Surgery alone | 91.4% (87.0%–94.4%) | 98.1% (95.0%–99.3%) | |
Adjuvant radiation therapy alone | 75.5% (46.9%–90.1%) | 88.2% (60.6%–96.9%) | 6.7% (1/15) |
Adjuvant chemotherapy ± radiation therapy | 65.6% (54.8%–74.5%) | 75.8% (65.3%–83.5%) | 10.8% (7/65) |
Neoadjuvant chemotherapy ± radiation therapy | 56.4% (49.3%–63.0%) | 70.4% (63.3%–76.4%) | 14.2% (16/113) |
Overall, local control after radiation therapy was as follows: R0, 106 of 109 patients (97%); R1, 51 of 60 patients (85%); and R2/unresectable, 2 of 6 patients (33%). Local recurrence predictors included extent of delayed resection (P < .001), imaging response before delayed surgery (P < .001), histological subtype (P < .001), and no radiation therapy (P = .046). The 5-year EFS was significantly lower for patients unable to undergo R0 or R1 resection (P = .0003).[85]
The authors concluded that adjuvant therapy could safely be omitted in the group of patients assigned to surgery alone. They also concluded that improving the outcome for patients with high-risk, initially resected, adult-type NRSTS and those with initially unresected disease remains a major clinical challenge.[84]
In a pooled analysis from U.S. and European pediatric centers, outcome was better for patients whose tumor removal procedure was deemed complete than for patients whose tumor removal was incomplete. Outcome was better for patients who received radiation therapy than for patients who did not.[81][Level of evidence C1]
Because long-term morbidity must be minimized while disease-free survival is maximized, the ideal therapy for each patient must be carefully and individually determined using these prognostic factors before initiating therapy.[29,86-90]
The WHO classification system for cancer represents the common nomenclature for cancer worldwide. In the United States, it has been adopted by the American Joint Committee on Cancer (AJCC) for sarcoma staging and the College of American Pathologists (CAP) cancer protocols for bone and soft tissue sarcomas. The WHO published a revision to their classification of soft tissue and bone tumors in 2020. The classification had several updates to existing classification, nomenclature, grading, and risk stratification schemes. The revised classification includes newly described entities, and it uses molecular alterations in the classifications.[1]
The grading of soft tissue tumors has always been a controversial issue. The 2020 WHO classification represents the consensus of several soft tissue pathologists and geneticists, as well as a medical oncologist, radiologist, and surgeon. This edition further integrates morphological and genetic information into the classification. For example, a new category of tumors called NTRK-rearranged spindle cell neoplasms was included, but infantile fibrosarcoma was excluded from this group. Ewing sarcoma was removed from the bone tumor section and, instead, is in the undifferentiated small cell sarcomas of bone and soft tissue section. This classification reflects the variable presentation sites and the variety of translocations seen in Ewing sarcoma. This classification also separated Ewing sarcoma from entities such as CIC-rearranged sarcomas, BCOR-rearranged sarcomas, and EWSR1 gene fusions involving non-ETS partner genes.[1]
Angioleiomyoma was reclassified under perivascular tumors.
With the increased use of next-generation sequencing techniques and heightened awareness of recently approved tyrosine kinase inhibitors that target NTRK and other genes, newer subgroups of pediatric soft tissue lesions that are characterized by kinase fusions have been identified and share a similar morphological spectrum. Identifying these rare entities is important because some of them might be amenable to therapeutic targeting with novel agents. Some examples of these lesions are described below.[4]
Clinical staging has an important role in predicting the clinical outcome and determining the most effective therapy for pediatric soft tissue sarcomas. As yet, there is no well-accepted staging system that is applicable to all childhood sarcomas. The system from the American Joint Committee on Cancer (AJCC) that is used for adults has not been validated in pediatric studies.
Although a standardized staging system for pediatric nonrhabdomyosarcomatous soft tissue sarcomas (NRSTS) does not exist, two systems are currently in use for staging pediatric NRSTS:[1]
The eighth edition of the AJCC Cancer Staging Manual has designated staging by the four criteria of tumor size, nodal status, histological grade, and metastasis and by anatomic primary tumor site (head and neck; trunk and extremities; abdomen and thoracic visceral organs; retroperitoneum; and unusual histologies and sites) (see Tables 5, 6, 7, and 8).[3-7] For information about unusual histologies and sites, see the AJCC Cancer Staging Manual.[7]
T Category | Soft Tissue Sarcoma of the Trunk, Extremities, and Retroperitoneum | Soft Tissue Sarcoma of the Head and Neck | Soft Tissue Sarcoma of the Abdomen and Thoracic Visceral Organs |
---|---|---|---|
aAdapted from O'Sullivan et al.,[3] Yoon et al.,[4] Raut et al.,[5] and Pollock et al.[6] | |||
TX | Primary tumor cannot be assessed. | Primary tumor cannot be assessed. | Primary tumor cannot be assessed. |
T0 | No evidence of primary tumor. | ||
T1 | Tumor ≤5 cm in greatest dimension. | Tumor ≤2 cm. | Organ confined. |
T2 | Tumor >5 cm and ≤10 cm in greatest dimension. | Tumor >2 to ≤4 cm. | Tumor extension into tissue beyond organ. |
T2a | Invades serosa or visceral peritoneum. | ||
T2b | Extension beyond serosa (mesentery). | ||
T3 | Tumor >10 cm and ≤15 cm in greatest dimension. | Tumor >4 cm. | Invades another organ. |
T4 | Tumor >15 cm in greatest dimension. | Tumor with invasion of adjoining structures. | Multifocal involvement. |
T4a | Tumor with orbital invasion, skull base/dural invasion, invasion of central compartment viscera, involvement of facial skeleton, or invasion of pterygoid muscles. | Multifocal (2 sites). | |
T4b | Tumor with brain parenchymal invasion, carotid artery encasement, prevertebral muscle invasion, or central nervous system involvement via perineural spread. | Multifocal (3–5 sites). | |
T4c | Multifocal (>5 sites). |
aAdapted from O'Sullivan et al.,[3] Yoon et al.,[4] Raut et al.,[5] and Pollock et al.[6] | |
bFor soft tissue sarcoma of the abdomen and thoracic visceral organs, N0 = no lymph node involvement or unknown lymph node status and N1 = lymph node involvement present. | |
N0 | No regional lymph node metastasis or unknown lymph node status.b |
N1 | Regional lymph node metastasis.b |
aAdapted from O'Sullivan et al.,[3] Yoon et al.,[4] Raut et al.,[5] and Pollock et al.[6] | |
bFor soft tissue sarcoma of the abdomen and thoracic visceral organs, M0 = no metastases and M1 = metastases present. | |
M0 | No distant metastasis.b |
M1 | Distant metastasis.b |
Stage | T | N | M | Grade |
---|---|---|---|---|
T = primary tumor; N = regional lymph node; M = distant metastasis. | ||||
aAdapted from Yoon et al. [4] and Pollock et al.[6] | ||||
bStage IIIB for soft tissue sarcoma of the retroperitoneum; stage IV for soft tissue sarcoma of the trunk and extremities. | ||||
IA | T1 | N0 | M0 | G1, GX |
IB | T2, T3, T4 | N0 | M0 | G1, GX |
II | T1 | N0 | M0 | G2, G3 |
IIIA | T2 | N0 | M0 | G2, G3 |
IIIB | T3, T4 | N0 | M0 | G2, G3 |
IIIB/IVb | Any T | N1 | M0 | Any G |
IV | Any T | Any N | M1 | Any G |
In most cases of soft tissue sarcomas, accurate histopathological classification alone does not yield optimal information about their clinical behavior. Therefore, several histological parameters are evaluated in the grading process, including the following:
This process is used to improve the correlation between histological findings and clinical outcome.[9] In children, grading of soft tissue sarcoma is complicated by certain factors, such as prognosis, patient age, extent of surgical resection, and ability to metastasize. For example, children younger than 4 years with infantile fibrosarcoma and hemangiopericytoma have a good prognosis, and angiomatoid fibrous histiocytoma and dermatofibrosarcoma protuberans can recur locally if incompletely excised but usually do not metastasize.
Testing the validity of a grading system within the pediatric population is difficult because of the rarity of these neoplasms. In March 1986, the Pediatric Oncology Group (POG) conducted a prospective study on pediatric NRSTS and devised the POG grading system. Analysis of outcome for patients with localized NRSTS demonstrated that patients with grade 3 tumors fared significantly worse than those with grade 1 or grade 2 lesions. This finding suggests that this system can accurately predict the clinical behavior of NRSTS.[9-11]
The POG and Fédération Nationale des Centres de Lutte Contre Le Cancer (FNCLCC) grading systems have proven to be of prognostic value in pediatric and adult NRSTS.[12-16] The COG uses the FNCLCC clinically. In a study of 130 tumors from children and adolescents with NRSTS enrolled in three prospective clinical trials, a correlation was found between the POG-assigned grade and the FNCLCC-assigned grade. However, grading did not correlate in all cases; 44 patients whose tumors received discrepant grades (POG grade 3, FNCLCC grade 1 or 2) had outcomes between concurrent grade 3 and grades 1 and 2. A mitotic index of 10 or greater emerged as an important prognostic factor.[17]
The COG ARST0332 (NCT00346164) trial compared the POG and FNCLCC pathological grading systems as part of a prospective risk-based strategy. The study found that, in addition to tumor depth and invasiveness, the FNCLCC grade was strongly associated with event-free survival and overall survival.[18] The closed COG ARST1321 (NCT02180867) trial used the FNCLCC system to assign histological grade.
The FNCLCC Sarcoma Group is described below. The POG grading system is no longer used.
The FNCLCC histological grading system was developed for adults with soft tissue sarcoma. The purpose of the grading system is to predict which patients will develop metastasis and subsequently benefit from postoperative chemotherapy.[19,20] For information about the FNCLCC histological grading system for adults, see the FNCLCC histological grade section in Soft Tissue Sarcoma Treatment.
Because of the rarity of pediatric nonrhabdomyosarcomatous soft tissue sarcomas (NRSTS), treatment should be coordinated by a multidisciplinary team that includes oncologists (pediatric or medical), pathologists, surgeons, and radiation oncologists for all children, adolescents, and young adults with these tumors. In addition, to better define the tumors' natural history and response to therapy, entry into national or institutional treatment protocols should be considered for children with rare neoplasms. Information about ongoing clinical trials is available from the NCI website.
The Children's Oncology Group (COG) performed a prospective nonrandomized trial (ARST0332 [NCT00346164]) for patients with soft tissue sarcomas.[1]
Surgical resection of the primary tumor was classified as follows:
Patients were assigned to one of the following three risk groups:
The treatment groups were as follows:
Chemotherapy included six cycles of intravenous (IV) ifosfamide (3 g/m2 per dose) on days 1 through 3 and five cycles of IV doxorubicin (37.5 mg/m2 per dose) on days 1 to 2 every 3 weeks, with the sequence adjusted on the basis of timing of surgery or radiation therapy.
The analysis included 529 evaluable patients: low risk (n = 222), intermediate risk (n = 227), and high risk (n = 80). Patients underwent surgery alone (n = 205), radiation therapy (n = 17), chemoradiation therapy (n = 111), and neoadjuvant chemoradiation therapy (n = 196).
At a median follow-up of 6.5 years (interquartile range [IQR], 4.9–7.9), the 5-year event-free survival (EFS) and overall survival (OS) rates, by risk group, were as follows:
The authors concluded that pretreatment clinical features can be used to effectively define treatment failure risk and stratify young patients with NRSTS for risk-adapted therapy. Most low-risk patients can be cured without adjuvant therapy, avoiding known long-term treatment complications. Survival remains suboptimal for intermediate-risk and high-risk patients, and novel therapies are needed for these patients.
Surgical resection of the primary tumor is the predominant therapy for most NRSTS. In the COG ARST0332 (NCT00346164) study, approximately 37% of patients younger than 30 years were treated with surgery alone.[1] Another 36% of patients had surgical resection after neoadjuvant chemoradiation therapy. Involvement of a surgeon with special expertise in the resection of soft tissue sarcomas is highly desirable.
After an appropriate biopsy and pathological diagnosis, every attempt is made to resect the primary tumor. Completeness of resection predicts outcome. In the COG ARST0332 study, complete resections with negative microscopic margins (R0) resulted in the best outcomes.[1]
The COG reported results for the subset of patients with low-grade NRSTS enrolled in the ARST0332 study.[2] Low-risk patients were treated with surgery alone. Intermediate- and high-risk patients received ifosfamide/doxorubicin and radiation therapy, with definitive resection either before or after 12 weeks of chemotherapy and radiation therapy.
Risk Group | 5-Year Event-Free Survival Rate | 5-Year Overall Survival Rate |
---|---|---|
Low risk | 90% | 100% |
Intermediate risk | 55% | 78% |
High risk | 25% | 25% |
The timing of surgery depends on an assessment of the feasibility and morbidity of surgery. In the COG ARST0332 study, the outcomes were nearly identical for intermediate-risk patients who achieved an R0 or R1 resection with up-front surgery or surgery after neoadjuvant chemoradiation therapy (70% vs. 71%, respectively). An R0 resection was more likely to occur after neoadjuvant therapy.[1] These observations are true even for high-grade tumors, where ability to achieve R0 or R1 resection was the major predictor of EFS. Treatment with neoadjuvant chemoradiation therapy resulted in lower doses of radiation therapy and achieved greater rates of R0 resection.[3] Resectability should be determined at the time of diagnosis, with an emphasis on achieving negative margins without loss of form or function.
If the initial operation fails to achieve pathologically negative tissue margins or if the initial surgery was done without the knowledge that cancer was present, a re-excision of the affected area is performed to obtain clear, but not necessarily wide, margins.[4-7] This surgical tenet is true even if no mass is detected by magnetic resonance imaging after initial surgery.[8]; [9][Level of evidence C1]
Regional lymph node metastases at diagnosis are unusual and are most often seen in patients with epithelioid and clear cell sarcomas.[10,11] Sentinel lymph node biopsy as a staging procedure in soft tissue sarcoma remains controversial. However, it may help manage selected cases in adults with clear cell sarcoma and epithelioid sarcoma. There are insufficient data to support the use of sentinel lymph node biopsy in the management of pediatric patients with other NRSTS.[12-17]
Considerations for radiation therapy are based on the potential for surgery, with or without chemotherapy, to obtain local control without loss of critical organs or significant functions, or causing cosmetic or psychological impairment. This will vary according to the following:
Radiation therapy can be given preoperatively or postoperatively. It can also be used as definitive therapy in rare situations in which surgical resection is not performed.[18] Radiation field size and dose will be based on patient and tumor variables and the surgical procedure.[19] Radiation therapy was associated with improved OS compared with surgery alone when delivered preoperatively or postoperatively.[20]
Brachytherapy and intraoperative radiation may be applicable in select situations.[21-23]; [24][Level of evidence C2]
Preoperative radiation therapy has been associated with excellent local control rates.[25-27] The advantages of this approach include treating smaller tissue volumes without the need to treat a postsurgical bed and somewhat lower radiation doses because relative hypoxia from surgical disruption of vasculature and scarring is not present. Preoperative radiation therapy has been associated with an increased rate of wound complications in adults, primarily in lower extremity tumors; however, the degree of these complications is questionable.[28] Conversely, preoperative radiation therapy may lead to less fibrosis than with postoperative approaches, perhaps because of the smaller treatment volume and dose.[29] Radiation technique can impact normal tissue sparing. Compared with 3-dimensional conformal radiation therapy, intensity-modulated radiation therapy offers the potential to decrease radiation dose to skin and epiphysis when irradiating extremity sarcomas.[30]
Radiation therapy can also be given postoperatively. In general, radiation is indicated for patients with inadequate surgical margins and for larger, high-grade tumors.[31,32] This is particularly important in high-grade tumors with tumor margins smaller than 1 cm.[33,34]; [35][Level of evidence C3] With combined R0 (negative margin) surgery and radiation therapy, local control of the primary tumor can be achieved in about 90% of patients with extremity sarcomas, 70% to 75% of patients with retroperitoneal sarcomas, and 80% of patients overall.[21,36-39]
Retroperitoneal sarcomas are unique in that the radiosensitivity of the bowel increases the risk of injury and makes postoperative radiation therapy less desirable.[40,41] Postoperative adhesions and bowel immobility can increase the risk of damage from any given radiation dose. This contrasts with the preoperative approach in which the tumor often displaces bowel outside of the radiation field, and any exposed bowel is more mobile, which decreases exposure to specific bowel segments.
Radiation volume and dose depend on the patient, tumor, and surgical variables noted above, as well as the following:
Radiation doses are typically 45 Gy to 50 Gy preoperatively, with consideration for postoperative boost of 10 Gy to 20 Gy if resection margins are microscopically or grossly positive, or planned brachytherapy if the resection is predicted to be subtotal. In addition, even in the preoperative setting, an additional boost of radiation at a dose of 60 Gy can be considered for areas of the tumor predicted to be at risk of residual microscopic disease (e.g., areas of tumor adjacent to critical normal tissues) that cannot be resected with adequate margins. This can be accomplished with a simultaneously integrated boost dose (i.e., higher dose area within the larger lower dose volume) or administered with a small field of radiation after the initial volume is treated with a dose of 45 Gy to 50 Gy. However, data documenting the efficacy of a postoperative boost to areas with microscopically positive margins are lacking.[42] The postoperative radiation dose is 55 Gy to 60 Gy for R0 resections, up to 65 Gy for R1 resections (microscopic positive margins), and higher when unresectable gross residual disease exists, depending on overall treatment goals (e.g., definitive local control vs. palliation).
The Children's Oncology Group analyzed local recurrence (LR) for NRSTS after radiation therapy in patients treated on ARST0332.[3] Patients younger than 30 years with high-grade NRSTS received radiation therapy (55.8 Gy) for an R1, 5 cm or smaller tumor (arm B); radiation therapy (55.8 Gy) with chemotherapy for an R0/R1, larger than 5 cm tumor (arm C); or neoadjuvant radiation therapy (45 Gy) with chemotherapy plus delayed surgery, chemotherapy, and postoperative boost to 10.8 Gy for an R0, smaller than 5 mm margins tumor or R1 tumor, or 19.8 Gy for R2 or unresected tumors (arm D).
Radiation margins are typically 2 cm to 4 cm longitudinally and encompass fascial planes axially.[43,44]
The role of postoperative chemotherapy remains unclear.[45]
Evidence (lack of clarity regarding postoperative chemotherapy):
The use of angiogenesis and mammalian target of rapamycin (mTOR) inhibitors has been explored in the treatment of adult soft tissue sarcomas but not in pediatrics.
Evidence (targeted therapy in adults with soft tissue sarcoma):
The COG and NRG Oncology cancer consortia conducted a randomized trial of pazopanib added to neoadjuvant chemotherapy (doxorubicin and ifosfamide) and preoperative radiation therapy in pediatric and adult patients with NRSTS. Patients whose tumors were larger than 5 cm and had intermediate- or high-grade disease were eligible. The end point of the trial was pathological tumor response after adjuvant therapy. Study entry was closed early because the planned interim analysis showed that the pathological response boundary was crossed. Eighty-one patients were enrolled, but only 42 (52%) were available for response data (17 patients from each group discontinued therapy for either progression, unacceptable toxicity, or patient or physician choice).[51]
Cancer in children and adolescents is rare, although the overall incidence has slowly increased since 1975.[1] Children and adolescents with cancer should be referred to medical centers that have a multidisciplinary team of cancer specialists with experience treating the cancers that occur during childhood and adolescence. This multidisciplinary team approach incorporates the skills of the following pediatric specialists and others to ensure that children receive treatment, supportive care, and rehabilitation to achieve optimal survival and quality of life:
For specific information about supportive care for children and adolescents with cancer, see the summaries on Supportive and Palliative Care.
The American Academy of Pediatrics has outlined guidelines for pediatric cancer centers and their role in the treatment of children and adolescents with cancer.[2] At these centers, clinical trials are available for most types of cancer that occur in children and adolescents, and the opportunity to participate is offered to most patients and their families. Multidisciplinary evaluation in pediatric cancer centers that have surgical and radiotherapeutic expertise is of critical importance to ensure the best clinical outcome for these patients. Although surgery with or without radiation therapy can be curative for a significant proportion of patients, the addition of chemotherapy might benefit subsets of children with the disease. Therefore, enrollment in clinical trials is encouraged. Clinical trials for children and adolescents with cancer are generally designed to compare potentially better therapy with current standard therapy. Other types of clinical trials test novel therapies when there is no standard therapy for a cancer diagnosis. Most of the progress in identifying curative therapies for childhood cancers has been achieved through clinical trials. Information about ongoing clinical trials is available from the NCI website.
Many therapeutic strategies for children and adolescents with soft tissue tumors are similar to those for adult patients, although there are important differences. For example, the biology of the neoplasm in pediatric patients may differ dramatically from that of the adult lesion. Additionally, limb-sparing procedures are more difficult to perform in pediatric patients. The morbidity associated with radiation therapy, particularly in infants and young children, may be much greater than that observed in adults.[3]
Improved outcomes with multimodality therapy in adults and children with soft tissue sarcomas over the past 20 years have caused increasing concern about the potential long-term side effects of this therapy in children. To maximize tumor control and minimize long-term morbidity, treatment must be individualized for children and adolescents with nonrhabdomyosarcomatous soft tissue sarcoma. These patients should be enrolled in prospective studies that accurately assess any potential complications.[4]
Adipocytic tumors account for less than 10% of soft tissue lesions in patients younger than 20 years. The most common adipocytic tumors in children are lipomas and lipoblastomas.
Table 10 summarizes the adipocytic neoplasms seen in pediatric patients and includes information about their corresponding clinico-pathological and molecular features.[1]
Adipocytic Tumors | Frequency [2,3] | Epidemiology | Predilection Site(s) | Histology | Cytogenetic/Molecular Alterations |
---|---|---|---|---|---|
M = male; F = female; HGMA2 = high-mobility group AT-hook 2; PLAG1 = pleomorphic adenoma gene 1; MDM2 = mouse double minute 2 homolog; FUS = fused in sarcoma; DDIT3 = DNA damage inducible transcript 3. | |||||
aReprinted from Seminars in Diagnostic Pathology, Volume 36, Issue 2, Putra J, Al-Ibraheemi A, Adipocytic tumors in Children: A contemporary review, Pages 95–104, Copyright 2019, with permission from Elsevier.[1] | |||||
Benign | |||||
Lipoma | 64%–70% (including variants) | • Solitary: M = F | Trunk. | Monotonous sheets of mature adipocytes. | Chromosomes 12q (HMGA2), 13q and 6p. |
• Multiple: M > F | |||||
• Uncommon in the first 2 decades of life. | |||||
• Most common between age 40–60 years. | |||||
Angiolipoma | 4%–28% | • M > F | Trunk and extremities. | • Mature adipocytic proliferation. | — |
• Most common in late teens or early twenties. | • Vascular proliferation (capillary proliferation with fibrin thrombi). | ||||
Lipoblastoma | 18%–30% | • M > F | Trunk and extremities. | • Lobular architecture. | Chromosome 8q (PLAG1) rearrangement. |
• Zones of maturation. | |||||
• <3 years old (90%) | • Primitive stellate cells. | ||||
• Multivacuolated lipoblasts. | |||||
• Myxoid area with prominent plexiform vessels. | |||||
Hibernoma | 2% | • M = F | Back (scapular area), chest wall, axilla and inguinal regions. | • Lobular architecture. | Chromosome 11q13-21 rearrangement. |
• Rare in the first 2 decades of life (5%). | • Different types of cells: brown fat cells, multivacuolated lipoblasts, mature fat cells. | ||||
• 60% occur in the 3rd and 4th decades of life. | • Prominent capillary network (less pronounced than lipoblastoma and myxoid liposarcoma). | ||||
Intermediate | |||||
Atypical lipomatous tumor/well-differentiated liposarcoma | Rare | • M = F | Extremities, head and neck, trunk. | • Mature adipocytic proliferation. | Supernumerary ring and giant marker chromosome 12q14-15 (MDM2). |
• Extremely rare in children (associated with Li-Fraumeni syndrome). | • Significant variation in size. | ||||
• Peak incidence is 6th decade of life. | • Hyperchromatic nuclei with atypia. | ||||
Malignant | |||||
Myxoid liposarcoma | 4% | • F > M | Extremities, trunk, head and neck and abdominal regions. | • Nodular architecture. | Recurrent t(12;16)(q13;p11) resulting in FUS::DDIT3 gene fusion. |
• Mixture of round to spindle nonlipogenic cells and lipoblasts. | |||||
• The most common liposarcoma in children (2nd decade of life), but less frequent than adults. | • Prominent myxoid stroma with chicken-wire vasculature. | ||||
• Variants seen in children: pleomorphic and spindle cell subtypes. | |||||
• Peak incidence is 4th and 5th decades of life. | • Progression to round cell morphology is uncommon in children. | ||||
Dedifferentiated liposarcoma | Rare | • Reported in an 8-year old with a well-differentiated liposarcoma.[4] | • Lower extremity in a single case report of pediatric patient.[4] | • Transition from a well-differentiated liposarcoma to nonlipogenic, high-grade sarcoma. | Supernumerary ring and giant marker chromosome 12q14-15 (MDM2). |
• Dedifferentiation occurs in up to 10% of well-differentiated liposarcomas in adults. | • Retroperitoneum (adults). | • Heterologous differentiation (5%–10%). | |||
• Peak incidence is 6th decade of life. | |||||
Pleomorphic liposarcoma | Rare/not reported | • Peak incidence of pleomorphic liposarcoma is 7th decade of life. | • Extremities (adults). | • Pleomorphic lipoblasts. | — |
• The subtype has been reported in the settings of Li-Fraumeni [5] and Muir-Torre syndromes.[6] | • Background of a high-grade, pleomorphic sarcoma (non-lipogenic). |
Liposarcoma is rare in the pediatric population and accounts for 3% of soft tissue sarcoma in patients younger than 20 years (see Table 1).
In a review of 182 pediatric patients with adult-type sarcomas, only 14 had a diagnosis of liposarcoma.[7] One retrospective study identified 34 patients younger than 22 years from 1960 to 2011.[8] There were roughly equal numbers of male and female patients, and the median age was 18 years. In an international clinico-pathological review, the characteristics of 82 cases of pediatric liposarcoma were reported.[9] The median age was 15.5 years, and females were more commonly affected. In both reports, most patients had myxoid liposarcoma.[8,9]
A literature review of 275 cases of pediatric liposarcoma showed that:[10]
Most liposarcomas in the pediatric and adolescent age range are low grade and located subcutaneously. Metastasis to lymph nodes is uncommon, and most metastases are pulmonary. Tumors arising in the periphery are more likely to be low grade and myxoid. Tumors arising centrally are more likely to be high grade, pleomorphic, and present with metastasis or recur with metastasis.
The World Health Organization (WHO) classification for liposarcoma is as follows:[11]
Higher grade or central tumors are associated with a significantly higher risk of death. In an international retrospective review, the 5-year survival rate was 42% for patients with central tumors. Seven of ten patients with pleomorphic myxoid liposarcoma died of their disease.[9] In a retrospective study of 14 patients, the 5-year survival rate was 78%. Tumor grade, histological subtype, and primary location correlated with survival.[8]
Treatment options for liposarcoma include the following:
Surgery is the most important treatment for liposarcoma. After complete surgical resection of well-differentiated or myxoid liposarcoma, the event-free survival (EFS) and overall survival (OS) rates are roughly 90%.[29] If initial surgery is incomplete, re-excision should be performed to achieve a wide margin of resection.[23-25] Local recurrences have been seen and are controlled with a second resection of the tumor, particularly for low-grade liposarcomas.
Chemotherapy has been used to decrease the size of liposarcoma before surgery to facilitate complete resection, particularly in central tumors.[30,31] The role of postoperative chemotherapy for liposarcoma is poorly defined. Postoperative therapy for completely resected myxoid liposarcomas does not appear to be needed. Even with the use of postoperative chemotherapy, the survival of patients with pleomorphic liposarcomas remains poor.[32]
There are very limited data to support the use of trabectedin in pediatric patients.[33] Trabectedin has produced encouraging responses in adults with advanced myxoid liposarcoma.[34] In one study, adult patients with recurrent liposarcoma and leiomyosarcoma were randomly assigned to treatment with either trabectedin or dacarbazine. Patients treated with trabectedin had a 45% reduction in disease progression.[35][Level of evidence B1]
Treatment with eribulin, a nontaxane microtubule dynamics inhibitor, significantly improved survival in adult patients with recurrent liposarcoma compared with dacarbazine. The median OS was 15.6 months for patients who received eribulin, versus 8.4 months for patients who received dacarbazine. Survival differences were more pronounced in patients with dedifferentiated and pleomorphic liposarcoma. Eribulin was effective in prolonging survival of patients with either high-grade or intermediate-grade tumors.[36][Level of evidence A1] A pediatric phase I trial of eribulin did not accrue any patients with liposarcoma.[37]
Radiation therapy is also considered either preoperatively or postoperatively depending on the cosmetic/functional consequences of additional surgery and radiation therapy.[38,39]
In a phase II, single-arm, multicenter study, 41 adult patients with unresectable or metastatic high-grade or intermediate-grade liposarcoma were treated with pazopanib at a dose of 800 mg daily.[28][Level of evidence B4]
Chondro-osseous tumors have several subtypes, including the following:
Osseous and chondromatous neoplasms account for 0.8% of soft tissue sarcomas in patients younger than 20 years (see Table 1). Mesenchymal chondrosarcoma is more common in the head and neck region.
Mesenchymal chondrosarcoma is a rare tumor characterized by small round cells and hyaline cartilage that more commonly affects young adults.
Mesenchymal chondrosarcoma has been associated with consistent chromosomal rearrangement. A retrospective analysis of cases of mesenchymal chondrosarcoma identified a HEY1::NCOA2 gene fusion in 10 of 15 tested specimens.[1] This gene fusion was not associated with chromosomal changes that could be detected by karyotyping. In one instance, translocation t(1;5)(q42;q32) was identified in a case of mesenchymal chondrosarcoma and shown to be associated with a novel IRF2BP::CDX1 gene fusion.[2]
A retrospective study analyzed 13 patients with mesenchymal chondrosarcoma, all with confirmed HEY1::NCOA2 gene fusions.[3]
A retrospective survey of European institutions identified 113 children and adults with mesenchymal chondrosarcoma. Factors associated with better outcome included the following:[4][Level of evidence C1]
A retrospective analysis of Surveillance, Epidemiology, and End Results (SEER) Program data from 1973 to 2011 identified 205 patients with mesenchymal chondrosarcoma; 82 patients had skeletal primary tumors, and 123 patients had extraskeletal tumors.[5] The outcomes of patients with skeletal and extraskeletal primary tumors were the same. Factors associated with outcome included the following:
A single-institution retrospective review identified 43 cases of mesenchymal chondrosarcoma from 1979 to 2010.[6] Thirty patients with localized disease were evaluated. The mean age at diagnosis was 33 years (range, 11–65 years).
Treatment options for extraskeletal mesenchymal chondrosarcoma include the following:
A review of 15 patients younger than 26 years from the German Cooperative Soft Tissue Sarcoma Study Group (11 with soft-tissue lesions) and the German-Austrian-Swiss Cooperative Osteosarcoma Study Group (four with primary bone lesions) protocols suggested that complete surgical removal, or incomplete resection followed by radiation therapy, was necessary for local control.[9][Level of evidence C1]
A single-institution, retrospective review identified 12 pediatric patients with mesenchymal chondrosarcoma.[10] Eleven patients presented with localized disease, and one patient presented with pulmonary nodules. Six patients received preoperative chemotherapy. All patients received postoperative chemotherapy (most commonly ifosfamide/doxorubicin) with or without radiation therapy (median dose, 59.4 Gy).
A Japanese study of patients with extraskeletal myxoid chondrosarcoma and mesenchymal chondrosarcoma randomly assigned patients to treatment with either trabectedin or best supportive care.[11] The median age of patients was 38 years (range, 21–77 years).
Extraskeletal osteosarcoma is extremely rare in the pediatric and adolescent population. Osseous and chondromatous neoplasms account for 0.8% of soft tissue sarcomas in patients younger than 20 years (see Table 1).
A review of 32 adult patients with extraskeletal osteosarcomas consistently revealed several alterations.[12] Frequent genomic alterations included copy number losses in CDKN2A (70%), TP53 (56%), and RB1 (49%). Variants were identified that affected methylation/demethylation (40%), chromatin remodeling (27%), and the WNT/SHH pathways (27%). Cases with simultaneous TP53 and RB1 biallelic copy number losses were associated with worse DFS and OS.
Extraskeletal osteosarcoma is associated with a high risk of local recurrence and pulmonary metastasis.[13]
A single-institution retrospective review identified 43 patients with extraskeletal osteosarcoma; 37 patients had localized disease, and 6 patients presented with metastatic disease. The median age was 55 years (range, 7–81 years). Seventy-five percent of patients received chemotherapy.[14]
In a review of 274 patients with extraskeletal osteosarcoma, the median age at diagnosis was 57 years (range, 12–91 years).[15][Level of evidence C1]
The European Musculoskeletal Oncology Society performed a retrospective analysis of 266 eligible patients with extraskeletal osteosarcoma treated between 1981 and 2014. Fifty patients (19%) presented with metastatic disease.[15]
An analysis of SEER Program data identified 256 patients (6%) with extraskeletal osteosarcoma among 4,173 patients with high-grade osteosarcoma from 1973 to 2009.[16]
Treatment options for extraskeletal osteosarcoma include the following:
Typical chemotherapy regimens used for osteosarcoma include some combination of cisplatin, doxorubicin, high-dose methotrexate, and ifosfamide.[13-15]
For more information about treatment of extraosseous osteosarcoma, including chemotherapy options, see Osteosarcoma and Undifferentiated Pleomorphic Sarcoma of Bone Treatment.
Fibroblastic and myofibroblastic tumors have several subtypes, including the following:
Desmoid-type fibromatosis has previously been called desmoid tumors or aggressive fibromatoses.
Desmoid-type fibromatosis has an extremely low potential to metastasize. The tumors are locally infiltrating, and surgical control can be difficult because of the need to preserve normal structures.
Desmoid-type fibromatosis has a high potential for local recurrence. These tumors have a highly variable natural history, including well documented examples of spontaneous regression.[1]
Most desmoid tumors are sporadic, but a small proportion may occur in association with a variant in the APC gene (associated with intestinal polyps and a high incidence of colon cancer). In a study of 519 patients older than 10 years with a diagnosis of desmoid-type fibromatosis, 39 patients (7.5%, a possible underestimation) were found to have familial adenomatous polyposis (FAP).[2] The patients with FAP and desmoid-type fibromatosis were younger, more often male, and had more abdominal wall or mesenteric tumors than did patients with desmoid-type fibromatosis without FAP.
Variants in exon 3 of the CTNNB1 gene are seen in more than 80% of desmoid-type fibromatosis cases. The 45F variant in exon 3 of the CTNNB1 gene has been associated with an increased risk of disease recurrence.[3] Repeated surgical resection can sometimes bring recurrent lesions under control.[4]
Currently, there are no general recommendations for genetic testing in children with desmoid-type fibromatosis. Pathological and molecular characteristics of the tumor only provide guidance for screening.
A family history of colon cancer, the presence of congenital hyperplasia of the retinal pigment epithelium,[5,6] or location of the desmoid-type fibromatosis in the abdomen or abdominal wall [2] should prompt referral to a genetic counselor. If the tumor has a somatic CTNNB1 variant, screening is not necessary, because the APC gene variant has not been described in this setting. If a CTNNB1 variant is not identified, screening for the APC variant may be warranted.[7,8]
Pediatric desmoid tumors can harbor additional variants in the AKT, BRAF V600E, TP53, and RET genes.[9] For more information, see the Familial Adenomatous Polyposis (FAP) section in Genetics of Colorectal Cancer.
Evaluating the benefit of treatment interventions for desmoid-type fibromatosis has been extremely difficult, because desmoid-type fibromatosis has a highly variable natural history, with partial regressions seen in up to 20% of patients.[10] Large adult series and smaller pediatric series have reported long periods of disease stabilization and even regression without systemic therapy.[4,11]; [12][Level of evidence C2] For instance, in a large placebo-controlled trial of sorafenib in adult patients with desmoid tumor, the patients who received no therapy (observation/placebo) demonstrated a 20% partial regression rate, and 46% of the patients in the placebo group had no progression at 1 year.[10]
Treatment options for desmoid-type fibromatosis include the following:
Because of the variable natural history of desmoid tumors, as outlined above, observation is sometimes a viable option. This is particularly the case for asymptomatic lesions, lesions that do not pose a danger to vital organs, and tumors that are incompletely resected.[4,13-19]
A global consensus meeting that involved sarcoma experts with experience in both adult and pediatric desmoid tumor was organized to define the appropriate management of these tumors. The Desmoid Tumor Working Group suggested that an initial active surveillance approach does not influence the efficacy of subsequent treatments. They suggested that active therapy should only be considered in cases of persistent progression. Active surveillance includes continuous monitoring with a first magnetic resonance imaging (MRI) within 1 to 2 months of diagnosis, followed by scans in 3- to 6-month intervals. When the disease is located in critical structures that may pose significant morbidity, such as the mesentery and head and neck region, earlier decisions toward an active therapy should be undertaken.[20]
Evidence (observation vs. initial surgery):
The lack of intervention, surgical or otherwise, has been questioned. The Toronto Hospital for Sick Children evaluated the emotional impact on patients with desmoid tumors during regular return visits to a cancer center for ongoing computed tomography (CT) or MRI scans and follow-up. For individuals with desmoid tumors, higher levels of anxiety were found, even when compared with sarcoma patients, which did not ease with treatment and continued throughout surveillance.[23][Level of evidence C1]
The following chemotherapy regimens have been used to treat desmoid-type fibromatosis:
Targeted therapy has been used to treat children and adults with desmoid-type fibromatosis.
Evidence (sorafenib):
Evidence (pazopanib):
The NOTCH pathway has been implicated in the development of desmoid tumors.[32] The NOTCH pathway/gamma-secretase inhibitor nirogacestat has been evaluated in adult and pediatric patients.
Evidence (nirogacestat):
NSAIDs such as sulindac have been used in single cases for desmoid-type fibromatosis; the responses seen were usually disease stabilization.[36]
Antiestrogen treatment, usually tamoxifen, plus sulindac has also resulted in disease stabilization.[37] A prospective trial of the combination of tamoxifen and sulindac reported few side effects, although asymptomatic ovarian cysts were common in girls. This combination showed relatively little activity, as measured by rates of response and PFS.[38][Level of evidence B4]
Surgical resection should be used judiciously in patients with desmoid tumors because spontaneous regression can occur in up to 20% of cases. Surgical resection is recommended when tumor enlargement threatens the airway or when symptoms such as pain are persistent. A watch-and-wait strategy is otherwise preferred.
If surgery is chosen, the intent is to achieve clear margins. However, a retrospective review of children who underwent surgery for desmoid-type fibromatosis at St. Jude Children’s Research Hospital (SJCRH) reported no correlation between surgical margins and risk of recurrence.[19] In this study, 10 of 39 patients experienced a recurrence after surgery, with a median interval time of 2.5 years.
Radiation has been used for unresectable and symptomatic desmoid-type fibromatosis or postoperatively for tumors with inadequate resections if progression would have morbid consequences. The potential long-term complications of radiation therapy, especially subsequent neoplasms, make this modality less appealing in younger patients.[39]
Postoperative radiation therapy can be considered when recurrence or progression would entail additional surgery that might cause functional or cosmetic compromise and if radiation is considered acceptable in terms of morbidities.
Information about National Cancer Institute (NCI)-supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.
Dermatofibrosarcoma is a rare tumor that can be present in all age groups, but many of the reported cases arise in children.[40-42] A review of 451 cases in children younger than 20 years in the SEER Program database found that the incidence was 1 case per 1 million. The incidence was highest among Black patients aged 15 to 19 years. The most common sites were the trunk and extremities, which is similar to what is found in adults.
Ninety-five percent of patients underwent surgery. The overall survival (OS) rate was 100% at 5 years, 98% at 15 years, and 97% at 30 years. Male patients had decreased survival compared with female patients (P < .05).[43][Level of evidence C1]
The tumor has a consistent chromosomal translocation t(17;22)(q22;q13) that juxtaposes the COL1A1 gene with the PDGFRB gene.
Guidelines for workup and management of dermatofibrosarcoma protuberans have been published.[44]
Treatment options for dermatofibrosarcoma protuberans include the following:
Most patients with dermatofibrosarcoma tumors can be cured by complete surgical resection. Wide excision with negative margins or Mohs/modified-Mohs surgery will prevent most tumors from recurring.[45] Despite the locally aggressive behavior of the tumor, lymph node or visceral metastasis rarely occurs.
Evidence (surgery):
In retrospective reviews, postoperative radiation therapy after incomplete excision may have decreased the likelihood of recurrence.[47,48] Metastatic disease is more likely after multiple recurrences, and radiation or other adjuvant therapy should be considered in patients with recurrences that cannot be managed surgically.[41,43]
When surgical resection cannot be accomplished or the tumor is recurrent, treatment with imatinib has been effective in adults.[49-51]
Evidence (imatinib):
Inflammatory myofibroblastic tumor is a rare mesenchymal tumor that is more common in children and adolescents.[53-55]
Inflammatory myofibroblastic tumors are rare tumors that affect soft tissues and visceral organs of children and young adults.[56] They rarely metastasize but tend to be locally invasive. Usual anatomical sites of disease include soft tissue, lungs, spleen, colon, and breast.[53] A review of 42 cases of pediatric inflammatory myofibroblastic tumor of the bladder was published in 2015.[57]
Epithelioid inflammatory myofibroblastic sarcoma is an uncommon subtype of inflammatory myofibroblastic tumors that shows a male predominance and can present from infancy through adulthood.[58-60] This subtype shows epithelioid morphology and a perinuclear or nuclear membrane pattern of immunostaining for ALK.[58] The most common site of presentation is the abdomen, although other primary sites have been reported.[58-60]
Roughly one-half of inflammatory myofibroblastic tumors exhibit a clonal variant that activates the ALK gene (encodes a receptor tyrosine kinase) at chromosome 2p23.[61]
Most cases of epithelioid inflammatory myofibroblastic sarcoma have RANBP2::ALK gene fusions. RRBP1::ALK gene fusions have also been reported.[58-60] Because RANBP2 localizes to the nuclear pore, this likely explains the perinuclear or nuclear membrane pattern of staining noted for ALK in epithelioid inflammatory myofibroblastic sarcoma.
ROS1 and PDGFRB kinase fusions were identified in 8 of 11 patients (73%) who were negative for ALK by immunohistochemistry.[62][Level of evidence C3]
Inflammatory myofibroblastic tumors recur frequently but are rarely metastatic.[53-55] Studies of children with inflammatory myofibroblastic tumor show 5-year survival rates higher than 80%.[63]
Epithelioid inflammatory myofibroblastic sarcoma is an aggressive tumor that is generally treated with surgery. Before the availability of ALK inhibitors, disease progression and high mortality rates were common.[58,59,64] Epithelioid inflammatory myofibroblastic sarcoma generally responds to ALK inhibitors but progression on therapy has been observed, which is consistent with the aggressive clinical behavior of the tumor.[60]
Treatment options for inflammatory myofibroblastic tumor include the following:
Complete surgical removal, when feasible, is the mainstay of therapy.[65]
Evidence (surgery with or without chemotherapy):
The benefit of chemotherapy has been noted in case reports.[69] A prospective registry of children with inflammatory myofibroblastic tumor from the European Soft Tissue Sarcoma Group (2005–2016) found an EFS rate of 82.9% and an OS rate of 98.1% at 5 years in all patients. The response rate for patients who received systemic therapy (chemotherapy or ALK inhibitor therapy) was 63% when used as front-line therapy and 66% when used as second-line therapy. Eight of ten patients who received vinblastine and low-dose methotrexate and all five patients who received ALK inhibitors (all of whom had ALK-positive tumors) responded to treatment.[63]
A retrospective, international, multicenter study analyzed patients younger than 21 years with ROS1-altered inflammatory myofibroblastic tumors who were enrolled in either the EpSSG NRSTS-2005 study or the Soft Tissue Sarcoma Registry. Primary surgery was recommended if a microscopic radical resection without disfigurement was feasible. Of the 19 patients, 12 received neoadjuvant systemic therapy as first-line treatment (high-dose steroids, n = 2; vinorelbine/vinblastine with methotrexate, n = 6; ROS1 inhibitors, n = 8). With a median follow-up of 2.8 years, seven patients had an event. The 3-year EFS rate was 41% (95% CI, 11%–71%), and the OS rate was 100%.[70]
There are case reports of response to either steroids or NSAIDs.[63,71,72]
Inflammatory myofibroblastic tumors respond to ALK inhibitor therapy, as follows:
Crizotinib
Evidence (crizotinib):
The U.S. Food and Drug Administration (FDA) approved crizotinib for patients aged 1 year and older with unresectable, recurrent, or refractory inflammatory ALK-positive myofibroblastic tumors.
Ceritinib
Evidence (ceritinib):
Alectinib
A case report described the successful treatment of a patient with an inflammatory myofibroblastic tumor and a FN1::ALK gene fusion using alectinib, a second-generation ALK inhibitor.[80]
For information about the treatment of this tumor in the lungs, see Childhood Pulmonary Inflammatory Myofibroblastic Tumors Treatment.
There are two distinct types of fibrosarcoma in children and adolescents, as follows:
These are two distinct pathological diagnoses and require different treatments.
Infantile fibrosarcoma usually occurs in children younger than 1 year. This tumor usually presents with a rapidly growing mass, often noted at birth or even seen in the prenatal ultrasound. The tumors are frequently quite large at the time of presentation.[82] Hypercalcemia secondary to elevated levels of parathyroid hormone–related protein has been reported as a presenting feature of this disease in newborns.[83]
These tumors have a low incidence of metastases at diagnosis.
The tumor usually has a characteristic cytogenetic translocation t(12;15)(p13;q25) to create the ETV6::NTRK3 fusion gene. Infantile fibrosarcoma shares this translocation and a virtually identical histological appearance with mesoblastic nephroma.
Infantile fibrosarcoma occasionally occurs in children up to age 4 years. A tumor with similar morphology has been identified in older children; in these older children, the tumors do not have the ETV6::NRTK3 fusion that is characteristic of the tumors in younger patients.[84] BRAF intragenic deletions have been described in cases of infantile fibrosarcoma and co-occur with NTRK3 fusions.[85] One study described four young children (aged 2–10 years) with tumors that were histologically classified as infantile fibrosarcoma and had ALK rearrangements.[86]
The Associazione Italiana Ematologia Oncologia Pediatrica analyzed a cohort of 44 pediatric patients with tumors classified as infantile fibrosarcomas/congenital mesoblastic nephromas. Eight infantile fibrosarcoma–like mesenchymal tumors found to be negative for the ETV6::NTRK3 fusion gene were analyzed by RNA sequencing to identify novel driver events. They identified three fusion genes involving RAF1: GOLGA4::RAF1, LRRFIP2::RAF1, and CLIP1::RAF1. The three fusion proteins retained the entire catalytic domain of the RAF1 kinase.[87]
Treatment options for infantile fibrosarcoma include the following:
Complete resection is curative in most patients with infantile fibrosarcoma. However, the large size of the lesion frequently makes resection without major functional consequences impossible. For instance, tumors of the extremities often require amputation for complete excision.
The European pediatric group has reported that observation may also be an option in patients with group II disease after surgery.[88] Twelve patients with group II disease received no further therapy and two patients relapsed. One patient obtained a complete remission after chemotherapy. Postoperative chemotherapy was administered to patients with higher group disease and those who progressed. In a subsequent study, only one of seven patients with group II disease progressed during observation; that patient achieved complete remission with chemotherapy.[89][Level of evidence C1]
A rare case of spontaneous regression without treatment has been reported.[90][Level of evidence C3]
Preoperative chemotherapy has made a more conservative surgical approach possible. Agents active in this setting include vincristine, dactinomycin, cyclophosphamide, and ifosfamide.[91,92]; [89,93,94][Level of evidence C1] Three older studies of patients with infantile fibrosarcoma suggested that an alkylator-free regimen was effective and used as the first treatment choice in patients with macroscopic disease.[88,89,95] However, newer results of studies using NTRK inhibitors have suggested that kinase inhibitors are an appropriate initial therapy.
Crizotinib
Evidence (crizotinib):
Larotrectinib
Larotrectinib is an oral ATP-competitive inhibitor of TRK A, B, and C.
Evidence (larotrectinib):
Other TRK inhibitors
Information about NCI-supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.
These tumors lack the translocation seen in infantile fibrosarcomas. They present like most nonrhabdomyosarcomas, and the management approach is similar.
Myxofibrosarcoma is a rare lesion, especially in childhood. It is typically treated with complete surgical resection.
Low-grade fibromyxoid sarcoma is a histologically deceptive soft tissue neoplasm that most commonly affects young and middle-aged adults. It is commonly located deep within the extremities.[105-107]
A Children's Oncology Group (COG) trial (ARST0332 [NCT00346164]) enrolled 11 patients with this tumor type. The median age at diagnosis was 13 years and males were more commonly affected. The most common tumor sites were the lower and upper extremities (n = 9). None of the patients developed local or distant disease recurrence at a median follow up of 2.7 years.[108]
Low-grade fibromyxoid sarcoma is characterized by a FUS::CREB3L2 gene translocation and, rarely, alternative gene translocations such as FUS::CREB3L1 and EWSR1::CREB3L1.[109,110]
In a review of 33 patients (3 were younger than 18 years) with low-grade fibromyxoid sarcoma, 21 patients developed a local recurrence after intervals of up to 15 years (median, 3.5 years). Fifteen patients developed metastases up to 45 years (median, 5 years) from diagnosis, most commonly to the lungs and pleura. This finding emphasizes the need for continued follow-up of these patients.[105] Even after metastases occur, the disease course may be indolent.[111]
In another report, 14 of 73 patients were younger than 18 years. In this series with a relatively short follow up (median of 24 months), only 8 of 54 patients with adequate follow-up developed local (9%) or distant (6%) recurrence. This report suggested that the behavior of this tumor might be significantly better than previously reported.[112] However, because late metastases can occur, careful monitoring of these patients is warranted.
Treatment options for low-grade fibromyxoid sarcoma include the following:
Low-grade fibromyxoid sarcoma is not very chemosensitive, and the limited treatment information suggests that surgery is the treatment of choice.[111]
Evidence (surgery):
There are little data regarding the use of chemotherapy and/or radiation therapy in this disease. One report suggests that trabectedin may be effective in the treatment of low-grade fibromyxoid sarcoma.[113]
Sclerosing epithelioid fibrosarcoma is a rare malignant sarcoma that commonly harbors EWSR1 gene fusions and has an aggressive clinical course. The tumor responds poorly to chemotherapy.[114,115]
Sclerosing epithelioid fibrosarcoma most commonly has the EWSR1::CREB3L1 gene fusion. However, EWSR1 may have other partners, including CREB3L2 and CREB3L3.[116,117] Gene fusions involving FUS (including the FUS::CREB3L2 fusion associated with low-grade fibromyxoid sarcoma) and PAX5 (e.g., PAX5::CREB3L1) are uncommon but can occur.[117,118] For cases of sclerosing epithelioid fibrosarcoma that lack MUC4 expression, EWSR1 gene fusions are generally absent, while a gene fusion involving YAP1 and KMT2A is commonly observed.[114,116,119,120] Sclerosing epithelioid fibrosarcoma has more structural and chromosomal segmental alterations than low-grade fibromyxoid fibrosarcoma.[116]
Treatment options for sclerosing epithelioid fibrosarcoma include the following:
The tumor responds poorly to chemotherapy.[121] Therefore, it is typically treated with complete surgical excision. Long-term follow-up is recommended because late local recurrences and metastases can occur.
Skeletal muscle tumors have several subtypes, including the following:
For more information, see Childhood Rhabdomyosarcoma Treatment.
Ectomesenchymoma is a rare skeletal muscle tumor that mainly occurs in children. It is a biphenotypic soft tissue sarcoma with both mesenchymal and ectodermal components.
A single-institution retrospective review identified seven cases of malignant ectomesenchymoma.[1] All seven patients were male, with a mean age of 7.5 months (range, 0.6–17.0 months). Five of the seven patients in this series were healthy and free of disease at the time of reporting.
A retrospective review of six patients with malignant ectomesenchymoma from a single institution identified rhabdomyosarcoma as the mesenchymal element in five of six tumors.[2] Tumors with an alveolar rhabdomyosarcoma morphology exhibited the characteristic translocation. No unifying molecular aberrations were identified.
A single-institution retrospective review identified seven cases of malignant ectomesenchymoma.[1] Most patients showed elements of embryonal rhabdomyosarcoma. The mixed neuroectodermal elements were scattered ganglion cells, ganglioneuroma, or ganglioneuroblastoma. Six of seven cases had HRAS variants. The trimethylation at lysine 27 of histone H3 (H3K27me3), typically lost in malignant peripheral nerve sheath tumor, was retained in all cases.
Treatment options for ectomesenchymoma include the following:
The Cooperative Weichteilsarkom Studiengruppe (CWS) reported on six patients (ages 0.2–13.5 years) registered over 14 years.[3][Level of evidence C1] The tumors were located in various sites including the extremities, abdomen, and orbit. All six patients were treated with surgery and chemotherapy directed at rhabdomyosarcoma. Two patients received radiation therapy. Three patients experienced tumor recurrences with rhabdomyosarcoma features. Although data are scant, it appears that the tumor may respond to chemotherapy.[3]
The European paediatric Soft Tissue Sarcoma Study Group (EpSSG) identified ten patients with ectomesenchymoma in a prospectively recorded database.[4] Of the ten cases, seven had an initial local diagnosis of rhabdomyosarcoma. All patients received chemotherapy according to rhabdomyosarcoma strategy, and four patients received radiation therapy. Overall, six patients were alive in first remission, two in second remission, and one after treatment for a second primary cancer. Only the patient with a metastatic tumor at diagnosis died of their disease.
Leiomyosarcoma accounts for 2% of soft tissue sarcomas in patients younger than 20 years (see Table 1).
Among 43 children with HIV/AIDS who developed tumors, 8 developed Epstein-Barr virus–associated leiomyosarcoma.[1] Survivors of hereditary retinoblastoma have a statistically significant increased risk of developing leiomyosarcoma, and 78% of these patients were diagnosed 30 or more years after the initial diagnosis of retinoblastoma.[2]
There are no standard treatment options for leiomyosarcoma in pediatric patients.
Trabectedin has been studied in adults with leiomyosarcoma. There are no studies using trabectedin to treat leiomyosarcoma in pediatric patients.
Results from studies in adults include the following:
Plexiform fibrohistiocytic tumor is a rare, low- to intermediate-grade tumor that most commonly affects children and young adults. The median age at presentation ranges from 8 to 14.5 years; however, the tumor has been described in patients as young as 3 months.[1,2]
The tumor commonly arises as a painless mass in the skin or subcutaneous tissue and most often involves the upper extremities, including the fingers, hand, and wrist.[3-5] Plexiform fibrohistiocytic tumor is an intermediate-grade tumor that rarely metastasizes. However, there are rare reports of the tumor spreading to regional lymph nodes or the lungs.[1,5,6]
No consistent chromosomal anomalies have been detected but a t(4;15)(q21;q15) translocation has been reported.[7]
Treatment options for plexiform fibrohistiocytic tumor include the following:
Surgery is the treatment of choice, but local recurrence has been reported in 12% to 50% of cases.[8]
Peripheral nerve sheath tumors have several subtypes, including the following:
Malignant peripheral nerve sheath tumors account for 5% of soft tissue sarcomas in patients younger than 20 years (see Table 1).
Malignant peripheral nerve sheath tumor can arise sporadically and in children with neurofibromatosis type 1 (NF1).[1] Among patients with NF1, a family history of malignant peripheral nerve sheath tumor is associated with an increased risk of developing early-onset malignant peripheral nerve sheath tumor.[2]
A rare case of a child with documented neurofibromatosis type 2 (NF2) and a benign neurofibroma had five recurrences. During this time, the lesions progressively lost markers (such as S-100) and acquired clear-cut signs of malignant transformation to malignant peripheral nerve sheath tumor, documented by multiple markers, including the first example of NOTCH2 in this disease.[3]
The molecular pathogenesis of adult malignant peripheral nerve sheath tumors demonstrates inactivating variants in at least three pathways, including NF1, CDKN2A, CDKN2B, and PRC2 complex core components. Similar alterations have been reported in pediatric tumors.[4]
The Memorial Sloan Kettering Cancer Center studied archival and consultation material from 64 pediatric and young adult patients (aged 20 years or younger).[4] Fifty-eight percent of patients had a clinical history of NF1. All but one patient had high-grade malignant peripheral nerve sheath tumors. Overall, 89% of patients were classified as having high-grade malignant peripheral nerve sheath tumors, and 94% of patients had conventional histological features. There were 16 high-grade tumors available for molecular characterization using the MSK-IMPACT assay. These pediatric and adolescent tumors had genomic driver events that were similar to those in adult tumors. The study found genomic perturbations in PRC2 components (SUZ12 or EED; 9 cases), NF1 variants (8 cases), and CDKN2A and CDKN2B deletions (8 cases). Loss of HDK27me3 expression was noted in 82% of conventional high-grade malignant peripheral nerve sheath tumors. This finding is a potentially powerful immunohistochemical diagnostic marker for pediatric malignant peripheral nerve sheath tumors.
Factors associated with a favorable prognosis include the following:[1,8-10]
Factors associated with an unfavorable prognosis include the following:[12]
Presence of NF1 appears to be associated with an unfavorable prognosis, but the data are mixed.[4,15]
For patients with localized disease in the MD Anderson Cancer Center study, there was no significant difference in outcome between patients with and without NF1.[9] In other studies, it was not clear whether the absence of NF1 was a favorable prognostic factor as it has been associated with both favorable [8] and unfavorable outcomes.[1,8,10]
In the French Sarcoma Group study, NF1 was associated with other adverse prognostic features, but was not an independent predictor of poor outcome.[12] A retrospective analysis of cancer registry data from the Netherlands identified 784 patients with malignant peripheral nerve sheath tumor; 70 of the patients were aged 18 years or younger.[16][Level of evidence C1] In children with NF1, large tumor size was more common (>5 cm, 92.3% vs. 59.1%). Overall, the estimated 5-year survival rate was 52.4% (standard error [SE], 10.1%) for patients with localized malignant peripheral nerve sheath tumor and NF1, compared with 75.8% (SE, 7.1%) for patients without NF1.
The Cooperative Weichteilsarkom Studiengruppe (CWS) reported a retrospective review of patients with malignant peripheral nerve sheath tumor who were treated on five consecutive CWS trials.[17] A total of 159 patients were analyzed. NF1 was reported in 38 patients (24%). Nodal involvement was documented in 15 patients (9%) at diagnosis, and distant metastases was noted in 15 patients (9%) at diagnosis. Overall, the event-free survival (EFS) rate was 40.5% at 5 years and 36.3% at 10 years. The overall survival (OS) rate was 54.6% at 5 years and 47.1% at 10 years. Older age, positive NF1 status, primary tumor site other than extremity, larger tumor size, higher Intergroup Rhabdomyosarcoma Study (IRS) group, presence of metastatic disease, and failure to achieve first complete remission were identified as adverse prognostic factors for EFS and/or OS in the univariate analysis.
Treatment options for malignant peripheral nerve sheath tumor include the following:
Complete surgical removal of the tumor, whenever possible, is the mainstay of treatment.
The role of radiation therapy is difficult to assess, but durable local control of known postoperative microscopic residual tumor is not ensured after radiation therapy.
Chemotherapy has achieved objective responses in childhood malignant peripheral nerve sheath tumor.
Evidence (chemotherapy):
For patients who received chemotherapy, treatment consisted of four courses of ifosfamide/doxorubicin and two courses of ifosfamide concomitant with radiation therapy (50.4–54 Gy).
Of 120 patients enrolled in Italian pediatric protocols from 1979 to 2004, an analysis identified 73 patients younger than 21 years with relapsed malignant peripheral nerve sheath tumor. Treatment options included surgery, radiation therapy, and chemotherapy.[23]
A retrospective study evaluated nine patients with unresectable or metastatic malignant peripheral nerve sheath tumor (seven patients were previously treated) who were treated with selinexor with or without doxorubicin. Three patients experienced a partial response that lasted for 3 months to longer than 8 months, and four patients had stable disease.[24]
Information about National Cancer Institute (NCI)-supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.
The following is an example of a national and/or institutional clinical trial that is currently being conducted:
Malignant triton tumors are now classified as a variant of malignant peripheral nerve sheath tumors. They occur most often in patients with NF1 and consist of neurogenic and rhabdomyoblastic components.[25] Most malignant triton tumors are reported in adults, although they may also arise in children and adolescents.[26]
Distinguishing between malignant triton tumors and NF1-altered rhabdomyosarcomas can be difficult. The genomic characteristics of malignant triton tumors can aid in differentiating between the two tumors. CDKN2A deep deletions and loss-of-function alterations in genes of the PRC2 complex (e.g., SUZ12 and EED1) are commonly observed in malignant triton tumors, while they are uncommon in NF1-altered rhabdomyosarcomas. The loss of PRC2 function leads to loss of H3K27me3 expression, a finding that is common in malignant triton tumors. H3K27me3 expression is generally maintained in rhabdomyosarcomas.[26-28]
Pericytic (perivascular) tumors have several subtypes, including the following:
Infantile hemangiopericytoma, a subtype of myopericytoma, is a highly vascularized tumor of uncertain origin.
For children with hemangiopericytomas, those younger than 1 year seem to have a better prognosis than do children older than 1 year.[1-3]
Histologically, hemangiopericytomas are composed of packed round or fusiform cells that are arranged around a complex vasculature, forming many branch-like structures. Hyalinization is often present. Infantile hemangiopericytomas have similar histology but many are multilobular with vasculature outside the tumor mass.[4]
Treatment options for infantile hemangiopericytomas include the following:
Evidence (chemotherapy):
Several studies have reported on soft tissue sarcomas in children that were more akin to infantile myofibromatosis or hemangiopericytoma.[6,7] Rather than the ETV6::NTRK3 fusion protein seen in congenital infantile fibrosarcoma, a LMNA::NTRK1 fusion protein was identified.[8] One patient carrying this fusion responded to crizotinib. For more information about infantile myofibromatosis, see the Infantile Myofibromatosis section.
Infantile myofibromatosis is a fibrous tumor of infancy and childhood that most commonly presents in the first 2 years of life.[9]
The lesion can present as a single subcutaneous nodule (myofibroma) most commonly involving the head and neck region, or lesions can affect multiple skin areas, muscle, and bone (myofibromatosis).[10-13]
Somatic gain-of-function PDGFRB variants have been identified in sporadic cases of infantile myofibromatosis, including activating point variants and in-frame indels and duplications.[14,15] PDGFRB variants are observed in most cases with multicentric nodules, but are less common in cases with solitary myofibroma.[15,16] Some PDGFRB variants that cause infantile myofibromatosis are sensitive to tyrosine kinase inhibitors like imatinib.[15,16]
An inherited autosomal dominant form of infantile myofibromatosis has been described. It is associated with germline variants of the PDGFRB gene, with the R561C variant being most commonly observed.[17-19] The R561C variant is a relatively weak activator of PDGFRB, which may explain the presence of additional PDGFRB variants with stronger activity in some familial infantile myofibromatosis cases.[16,17]
The European Society for Paediatric Oncology Host Genome Working Group developed counseling and germline testing guidelines for these groups of children. This group recommends germline analysis for children with infantile myofibromatosis who have at least one of the following criteria:[20]
Patients with these tumors usually have an excellent prognosis and the tumors can regress spontaneously. However, about one-third of cases with multicentric involvement will also have visceral involvement, and the prognosis for these patients is poor.[12,13,21]
Treatment options for infantile myofibromatosis include the following:
Ninety-five patients were prospectively enrolled in five Cooperative Weichteilsarkom Studiengruppe (CWS) trials and one registry trial between 1981 and 2016.[22] Localized disease was diagnosed in 71 patients. Forty-two (59%) of these patients were infants younger than 12 months. The mainstay of treatment (applied to 55 children) was watch and wait after initial biopsy or resection. Systemic therapy was only recommended in cases of life-threatening progressive disease or in cases of compression of vital structures or organ dysfunction in the setting of progressive disease. Based on these criteria, chemotherapy was administered to 16 of 71 patients as an individual decision at the treating center: 8 patients received methotrexate/vinblastine, 5 patients received vincristine/dactinomycin/cyclophosphamide (VAC), and 3 patients received other therapies.
The use of combination chemotherapy with vincristine/dactinomycin and vinblastine/methotrexate have proven effective in cases of multicentric disease with visceral involvement and in cases in which the disease has progressed and has threatened the life of the patient (e.g., upper airway obstruction).[12,13,23]
Case reports have described prompt tumor regression in patients with infantile myofibromatosis that have PDGFRB variants when treated with tyrosine kinase inhibitors like imatinib and sunitinib, which inhibit the PDGFRB gain-of-function variant in the tumor.[24-27]
Tumors of uncertain differentiation have many subtypes, including the following:
Carney complex is an autosomal dominant syndrome caused by variants in the PRKAR1A gene, located on chromosome 17.[1] The syndrome is characterized by cardiac and cutaneous myxomas, pale brown to brown lentigines, blue nevi, primary pigmented nodular adrenocortical disease causing Cushing syndrome, and a variety of endocrine and nonendocrine tumors, including pituitary adenomas, thyroid tumors, and large cell calcifying Sertoli cell tumor of the testis.[1-3] There are published surveillance guidelines for patients with Carney complex that include cardiac, testicular, and thyroid ultrasonography.
For patients with the Carney complex, prognosis depends on the frequency of recurrences of cardiac and skin myxomas and other tumors.
For more information about the treatment of conditions related to Carney complex, see the following summaries:
Synovial sarcoma accounts for 9% of soft tissue sarcomas in patients younger than 20 years (see Table 1).
Synovial sarcoma is one of the most common nonrhabdomyosarcomatous soft tissue sarcoma (NRSTS) in children and adolescents. In a review of the Surveillance, Epidemiology, and End Results (SEER) Program database from 1973 to 2005, 1,268 patients with synovial sarcoma were identified. Approximately 17% of these patients were children and adolescents, and the median age at diagnosis was 34 years.[4] In addition, in the Children's Oncology Group (COG) ARST0332 (NCT00346164) and European paediatric Soft Tissue Sarcoma Study Group (EpSSG) 2005 protocols, synovial sarcoma was the single most common histological subtype.[5]
The most common primary tumor location is the extremities, followed by trunk and head and neck.[4] Rarely, a synovial sarcoma may arise in the heart or pericardium or appear with a pleuropulmonary presentation.[6-9]
The most common site of metastasis is the lung.[10,11] The risk of metastases is highly influenced by tumor size. Patients with tumors that are larger than 5 cm have an estimated 32-fold higher risk of developing metastases compared with other patients.
The Cooperative Weichteilsarkom Studiengruppe (CWS) reported on 432 patients younger than 21 years diagnosed with synovial sarcoma between 1981 and 2018.[12] The study compared three age groups of patients: children (aged 0–12 years; n = 176), adolescents (aged 13–16 years; n = 178), and young adults (aged 17–21 years; n = 78).
Synovial sarcoma can be subclassified as the following types:
The diagnosis of synovial sarcoma is made by immunohistochemical analysis, ultrastructural findings, and demonstration of the specific chromosomal translocation t(x;18)(p11.2;q11.2). This abnormality is specific for synovial sarcoma and is found in all morphological subtypes. Synovial sarcoma results in rearrangement of the SS18 gene on chromosome 18 with one of the subtypes (1, 2, or 4) of the SSX gene on chromosome X.[13,14] It is thought that the SS18::SSX fusion transcript promotes epigenetic silencing of key tumor suppressor genes.[15]
In one report, reduced SMARCB1 nuclear reactivity on immunohistochemical staining was seen in 49 cases of synovial sarcoma, suggesting that this pattern may help distinguish synovial sarcoma from other histologies.[16]
Favorable prognostic factors
Patients younger than 10 years have more favorable outcomes and clinical features than do older patients.
Favorable clinical features include the following:[4,17-19]
Unfavorable prognostic factors
The following studies have reported multiple factors associated with unfavorable outcomes:
Treatment options for synovial sarcoma include the following:
Evidence (surgery alone):
Synovial sarcoma appears to be more sensitive to chemotherapy than many other soft tissue sarcomas. Children with synovial sarcoma seem to have a better prognosis than do adults with synovial sarcoma.[11,28,32-37]
The most commonly used chemotherapy regimens for the treatment of synovial sarcoma incorporate ifosfamide and doxorubicin.[19,35,38] Response rates to the ifosfamide and doxorubicin regimen are higher than in other NRSTS.[39]
Evidence (surgery and chemotherapy with or without radiation therapy):
Outcomes for patients treated on the CCLG-EPSSG-NRSTS-2005 trial are described in Table 11.
Risk Group | Treatment | 3-Year EFS (%) | 3-Year OS (%) |
---|---|---|---|
IRS = Intergroup Rhabdomyosarcoma Study; RT = radiation therapy. | |||
aChemotherapy was ifosfamide/doxorubicin, with doxorubicin omitted during radiation therapy. | |||
b59.4 Gy in cases without the option of secondary resection; 50.4 Gy as preoperative radiation therapy; 50.4, 54, and 59.4 Gy as postoperative radiation therapy, in the case of R0, R1, and R2 resections, respectively (no additional radiation therapy in the case of secondary complete resections with free margins, in children younger than 6 years). | |||
Low | Surgery alone | 92 | 100 |
Intermediate | Surgery, 3–6 cycles chemotherapya, ± RTb | 91 | 100 |
High (IRS group III) | 3 cycles of chemotherapya, surgery, 3 additional cycles of chemotherapy, ± RTb | 77 | 94 |
High (axial primary sites) | Surgery, 6 cycles of chemotherapya, RTb | 78 | 100 |
Radiation Therapy | # Patients | 5-Year EFS Rate | 5-Year OS Rate | 5-Year Local Recurrence-Free Survival Rate |
---|---|---|---|---|
EFS= event-free survival; OS = overall survival. | ||||
No radiation therapy | 23 | 44% | 57% | 76% |
Radiation therapy before surgery | 57 | 70% | 83% | 98% |
Radiation therapy after surgery | 52 | 73% | 82% | 86% |
For patients with recurrent synovial sarcoma, the survival rate after relapse is poor (30%–40% at 5 years). Factors associated with outcome after relapse include duration of first remission (> or ≤ 18 months) and lack of a second remission.[46,47]
In a German experience, surgical resection of metastatic disease was the most common way to achieve a second complete remission.[47] Maintenance chemotherapy with oral trofosfamide, idarubicin, and etoposide or oral cyclophosphamide and intravenous vinblastine was administered on an individual basis.
A consortium of six European referral centers reported a retrospective review of patients younger than 21 years with recurrent synovial sarcoma. Among 41 patients, the first relapses occurred within 3 to 132 months (median, 18 months) after first diagnoses. The relapses were local in 34% of patients, metastatic in 54%, and both in 12%. Treatments at first relapse included surgery in 56% of patients, radiation therapy in 34%, and systemic therapy in 88%. In all, 36 patients received second-line medical treatment, which included chemotherapy in 32 patients (with 10 different regimens) and targeted therapy in 4 patients. No patient was included in early-phase clinical trials as second-line therapy. The overall response rate was 42%. The median EFS was 12 months, and the postrelapse 5-year EFS rate was 15.8%. The median OS was 30 months, and the postrelapse 5-year OS rate was 22.2%. In a Cox multivariable regression analysis, OS was significantly associated with time and type of relapse.[48]
Radiation therapy (stereotactic body radiation therapy) can be used to target select pulmonary metastases. This is usually considered after a minimum of one resection to confirm metastatic disease. Radiation therapy is particularly appropriate for patients with lesions that threaten air exchange because of their location adjacent to bronchi or cause pain by invading the chest wall.[49]
Between 70% to 80% of synovial sarcomas express NY-ESO-1, an immunogenic cancer testis antigen.[50] NY-ESO-1 can be targeted with adoptive transfer of T cells engineered to express NY-ESO-1c259, an affinity-enhanced T-cell receptor (TCR) targeting NY-ESO-1/LAGE1a.[51] The procedure to produce the genetically engineered T cells restricts their reactivity to a single HLA type. All clinical trials of this technology chose HLA-A*02 as the initial target and limited eligibility to patients whose tumors expressed NY-ESO-1 and who had HLA-A*02. In a multi-institutional trial, confirmed antitumor responses occurred in 50% of patients (6 of 12) and were characterized by tumor shrinkage over several months. Circulating NY-ESO-1c259T cells were present postinfusion in all patients, and the cells persisted for at least 6 months in all responders.[52]
Information about National Cancer Institute (NCI)-supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.
Epithelioid sarcoma is a rare mesenchymal tumor of uncertain histogenesis that displays multilineage differentiation.[53]
Epithelioid sarcoma commonly presents as a slowly growing firm nodule based in the deep soft tissue. The proximal type predominantly affects adults and involves the axial skeleton and proximal sites. The tumor is highly aggressive and has a propensity for lymph node metastases.
Epithelioid sarcoma is characterized by inactivation of the SMARCB1 gene, which is present in both conventional and proximal types of epithelioid sarcoma.[54] This abnormality leads to increased dependence on EZH2 and tumor formation.[55]
Treatment options for epithelioid sarcoma include the following:
Surgical removal of primary and recurrent tumor(s) is the most effective treatment.[56][Level of evidence C1] Because of the propensity of this disease to have occult metastasis to the lymph nodes, sentinel lymph node biopsy is recommended for epithelioid sarcoma of the extremities or buttocks in the absence of clinically (by imaging or physical examination) enlarged lymph nodes.[57]
Evidence (surgery with or without chemotherapy and/or radiation therapy):
Evidence (tazemetostat):
In January 2020, the U.S. Food and Drug Administration (FDA) granted accelerated approval for tazemetostat for adults and pediatric patients aged 16 years and older with metastatic or locally advanced epithelioid sarcoma who were not eligible for complete resection.
Information about NCI-supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.
The following is an example of a national and/or institutional clinical trial that is currently being conducted:
Alveolar soft part sarcomas account for 1.4% of soft tissue sarcomas in patients younger than 20 years (see Table 1).
The median age at presentation is 25 years for patients with alveolar soft part sarcoma. This tumor most commonly arises in the extremities but can occur in the oral and maxillofacial region.[62-64] Alveolar soft part sarcoma in children can present with evidence of metastatic disease.[65] Delayed metastases to the brain and lung are uncommon.[62]
In a series of 61 patients with alveolar soft part sarcoma who were treated in four consecutive CWS trials and the Soft Tissue Sarcoma Registry (SoTiSaR), 46 patients presented with localized disease and 15 patients had evidence of metastasis at diagnosis.[66]
Sixty-nine patients younger than 30 years with alveolar soft part sarcoma were treated between 1980 and 2014 at four major institutions. The median age at diagnosis was 17 years, and 64% of patients were female. The most common site of disease was the lower extremity, and 26 patients had an ASPSCR1::TFE3 gene translocation.[67]
This tumor of uncertain histogenesis is characterized by a consistent chromosomal translocation t(X;17)(p11.2;q25) that fuses the ASPSCR1 gene with the TFE3 gene.[68,69]
In patients with alveolar soft part sarcoma, presentation with metastases is common and often has a prolonged indolent course.
Alveolar soft part sarcoma in children may have an indolent course.[65] Patients with alveolar soft part sarcoma may relapse several years after a prolonged period of apparent remission.[66,70]
Treatment options for alveolar soft part sarcoma include the following:
The standard treatment approach is complete resection of the primary lesion.[71] If complete excision is not feasible, radiation therapy is administered.
Evidence (surgery with or without chemotherapy):
Studies of targeted therapy (tyrosine kinase inhibitors and checkpoint inhibitors) have been done.
Sunitinib
Evidence (sunitinib):
Cediranib
Cediranib is an inhibitor of all three known vascular epidermal growth factor receptors.
Evidence (cediranib):
Pazopanib
Evidence (pazopanib):
Axitinib and pembrolizumab
Axitinib is a vascular endothelial growth factor receptor tyrosine kinase inhibitor. Pembrolizumab is an anti–programmed cell death protein 1 immune checkpoint inhibitor.
Evidence (axitinib and pembrolizumab):
There have been sporadic reports of objective responses to treatment with interferon-alpha and bevacizumab.[62,81,82]
Because these tumors are rare, all children with alveolar soft part sarcoma should be considered for enrollment in prospective clinical trials. Information about ongoing clinical trials is available from the NCI website.
Information about NCI-supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.
Clear cell sarcoma (formerly called malignant melanoma of soft parts) is a rare soft tissue sarcoma that typically involves the deep soft tissues of the extremities. It is also called clear cell sarcoma of tendons and aponeuroses. The tumor often affects adolescents and young adults.
The tumor most commonly affects the lower extremity, particularly the foot, heel, and ankle.[83,84] It has a high propensity for nodal dissemination, especially metastases to regional lymph nodes (12%–43%).[84,85]
The tumor typically has an indolent clinical course. Patients who have small, localized tumors with low mitotic rate and intermediate histological grade have the best outcomes.[86]
Clear cell sarcoma of soft tissue is characterized by EWSR1::ATF1 or EWSR1::CREB1 gene fusions.[87,88]
Treatment options for clear cell sarcoma of soft tissue include the following:
Surgery with or without radiation therapy is the treatment of choice and offers the best chance for cure.
Evidence (surgery with or without radiation therapy):
Evidence (targeted therapy):
Extraskeletal myxoid chondrosarcoma is relatively rare among soft tissue sarcomas, representing only 2.3% of all soft tissue sarcomas.[92] It has been reported in children and adolescents.[93]
The tumor has traditionally been considered to have low-grade malignant potential.[94] However, reports from large institutions showed that extraskeletal myxoid chondrosarcoma has significant malignant potential, especially if patients are monitored for a long time.[95,96] Patients tend to have slow protracted courses. Nodal involvement has been well described. Local recurrence (57%) and metastatic spread to lungs (26%) have been reported.[96]
Extraskeletal myxoid chondrosarcoma is a multinodular neoplasm. The rounded cells are arranged in cords and strands in a chondroitin sulfate myxoid background. Several cytogenetic abnormalities have been identified (see Table 2), with the most frequent being the EWSR1::NR4A3 gene fusion.[97]
Treatment options for extraskeletal myxoid chondrosarcoma include the following:
Aggressive local control and resection of metastases led to OS rates of 87% at 5 years and 63% at 10 years. Tumors were relatively resistant to radiation therapy.[95] The therapeutic benefit of chemotherapy has not been established.
There may be potential genetic targets for small molecules, but these need to be studied as part of a clinical trial. In an adult study, six of ten patients who received sunitinib achieved partial responses.[98]
Almost one-fifth of patients with Ewing sarcoma will present with nonbone primary sites (extraosseous). Treatment for this tumor is the same as it is for patients with bone primary tumors.[99] For more information, see Ewing Sarcoma and Undifferentiated Small Round Cell Sarcomas of Bone and Soft Tissue Treatment.
Desmoplastic small round cell tumor is a rare primitive sarcoma.
Desmoplastic small round cell tumor most frequently involves the peritoneum in the abdomen, pelvis, and/or peritoneum into the scrotal sac, but it may occur in the kidney or other solid organs.[100-104] Dozens to hundreds of intraperitoneal implants are often found. The tumor occurs predominantly in males (85%) and may spread to the lungs and elsewhere.[104,105]
A large single-institution series of 65 patients compared computed tomography (CT) scans (n = 54) with positron emission tomography (PET)-CT scans (n = 11). PET-CT scans had very few false-negative results and detected metastatic sites missed on conventional CT scans.[105]
Cytogenetic studies of these tumors have demonstrated the recurrent translocation t(11;22)(p13;q12), which has been characterized as a fusion of the WT1 and EWSR1 genes.[103,106] The EWSR1::WT1 fusion confirms the diagnosis of desmoplastic small round cell tumor. The average tumor variant burden is low for desmoplastic small round cell tumor (<1 variant per megabase), and recurring gene alterations other than the EWSR1::WT1 fusion are uncommon.[107] A small percentage of cases (approximately 3%) have activating variants in FGFR4, with amplification of FGFR4 observed at similar frequency.[107,108] Inactivating variants in TP53 and ARID1A are observed in a small percentage of desmoplastic small round cell tumor cases.[107,108]
The overall prognosis for patients with desmoplastic small round cell tumor remains extremely poor, with reported rates of death at 90%. Greater than 90% tumor resection either at presentation or after preoperative chemotherapy may be a favorable prognostic factor for OS.[109,110]; [111][Level of evidence C1] Response to neoadjuvant chemotherapy and complete resection (near 100%) is associated with improved outcome.[104,112]
There is no standard approach to the treatment of desmoplastic small round cell tumor.
Treatment options for desmoplastic small round cell tumor include the following:
Complete surgical resections are rare and usually performed in highly specialized centers, but are critical for any improved survival. Successful treatment modalities include neoadjuvant Ewing-type chemotherapy, followed by complete surgical resection of the extensive intra-abdominal tumors, followed by total abdominal radiation therapy. With this multimodality approach, survival can be achieved in 30% to 40% of patients at 5 years.[100,101,109,113-116]
HIPEC is a local treatment method that may control more of the microscopic intra-abdominal disease. The theory is that the heated chemotherapy that is instilled in the abdominal cavity after surgical resection (at the time of surgery) provides synergistic cytotoxicity to any microscopic cells remaining in the abdomen.[117]
The addition of HIPEC to complete surgical resection (cytoreductive surgery) is a new technique first applied to children in 2006 in a phase I clinical trial. Cytoreductive surgery and HIPEC for desmoplastic small round cell tumors is part of a multidisciplinary approach and is only being done in highly specialized centers. Surgeries can last more than 12 hours, and technical aspects of this unique tumor resection should be considered.[117]
Evidence (surgery with HIPEC):
The Center for International Blood and Marrow Transplant Research analyzed patients with desmoplastic small round cell tumor in their registry who received consolidation with high-dose chemotherapy and autologous stem cell reconstitution.[121] While this retrospective registry analysis suggested some benefit to this approach, other investigators have abandoned the approach because of excessive toxicity and lack of efficacy.[109]
A single-institution study reported that five of five patients with recurrent desmoplastic small round cell tumor had partial responses to treatment with the combination of vinorelbine, cyclophosphamide, and temsirolimus.[122]
Malignant rhabdoid tumors were first described in children with renal tumors in 1981. These tumors were later found in a variety of extrarenal sites. These tumors are uncommon and highly malignant, especially in children younger than 2 years. For more information, see the Rhabdoid Tumors of the Kidney section in Wilms Tumor and Other Childhood Kidney Tumors Treatment.
Extrarenal (extracranial) rhabdoid tumors account for 2% of soft tissue sarcomas in patients younger than 20 years (see Table 1).
The first sizeable series of children with extrarenal extracranial malignant rhabdoid tumor of soft tissues came from 26 patients enrolled on the IRS I through III studies during a review of pathology material. Only five patients (19%) were alive without disease beyond 2 years.[123]
Investigation of children with atypical teratoid/rhabdoid tumors of the brain, as well as those with renal and extrarenal malignant rhabdoid tumors, found germline and acquired variants of the SMARCB1 gene in all 29 tumors tested.[124] Rhabdoid tumors may be associated with germline variants of the SMARCB1 gene and may be inherited from an apparently unaffected parent.[125] This observation was extended to 32 malignant rhabdoid tumors at all sites in patients whose mean age at diagnosis was 12 months.[126]
Germline analysis should be considered for individuals of all ages with rhabdoid tumors. Genetic counseling is also part of the treatment plan, given the low-but-actual risk of familial recurrence. In cases of variants, parental screening should be considered, although such screening carries a low probability of positivity. Prenatal diagnosis can be performed in situations where a specific SMARCB1 variant or deletion has been documented in the family.[125]
To date, there is little evidence regarding the effectiveness of surveillance for patients with rhabdoid tumor predisposition syndrome type 1 caused by loss-of-function germline SMARCB1 variants. However, because of the aggressive nature of the tumors with significant lethality and young age of onset in SMARCB1 carriers with truncating variants, consensus recommendations have been developed. These recommendations were developed by a group of pediatric cancer genetic experts (including oncologists, radiologists, and geneticists). They have not been formally studied to confirm the benefit of monitoring patients with germline SMARCB1 variants. Given the potential survival benefit of surgically resectable disease, it is postulated that early detection might improve OS.[127-129]
Surveillance for patients with germline SMARCB1 variants includes the following:
For information about SMARCB1 and rhabdoid tumor predisposition syndrome type 1, see Rhabdoid Tumor Predisposition Syndrome Type 1.
Young age and metastatic disease at presentation are associated with poor outcome in children with extracranial rhabdoid tumors.
One study that used data from the National Cancer Database identified 202 patients (aged younger than 18 years) with non–central nervous system (CNS) malignant rhabdoid tumors. The primary site of the malignant rhabdoid tumor was soft tissue (46%), kidney (45%), and liver (9%).[130]
A SEER study examined 229 patients with renal, CNS, and extrarenal malignant rhabdoid tumor. Patient age of 2 to 18 years, limited extent of tumor, and delivery of radiation therapy were shown to affect the outcome favorably compared with other patients (P < .002 for each comparison). Site of the primary tumor was not prognostically significant. The OS rate was 33% at 5 years.[131]
A European registry for extracranial rhabdoid tumors identified 100 patients from 14 countries between 2009 and 2018.[132] Half of the patients were younger than 1 year at diagnosis. In 30 patients (30%), the tumor was located in the kidneys. Extracranial, extrarenal malignant rhabdoid tumor was found in 70% of patients (70 of 100), and the most common locations were in the cervical region, thoracic region, and liver. Nine patients demonstrated synchronous tumors. Distant metastases at diagnosis were present in 35% of patients (35 of 100). SMARCB1 germline variants were detected in 21% of patients (17 of 81 evaluable). The 5-year OS rate was 45.8% (± 5.4%), and the EFS rate was 35.2% (± 5.1%). In an adjusted multivariate model, presence of a germline variant, metastasis, and lack of a gross-total resection were the strongest significant negative predictors of outcome.
Treatment options for extrarenal (extracranial) rhabdoid tumor include the following:[133-135][Level of evidence C1]
Responses to alisertib have been documented in four patients with CNS atypical teratoid/rhabdoid tumors.[136] For more information about CNS atypical teratoid/rhabdoid tumors, see Childhood Central Nervous System Atypical Teratoid/Rhabdoid Tumor Treatment.
Information about NCI-supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.
The following is an example of a national and/or institutional clinical trial that is currently being conducted:
PEComas occur in various rare gastrointestinal, pulmonary, gynecological, and genitourinary sites. Soft tissue, visceral, and gynecological PEComas are more commonly seen in middle-aged female patients and are usually not associated with the tuberous sclerosis complex.[137] The disease course may be indolent.
Benign PEComas are common in patients with tuberous sclerosis, an autosomal dominant syndrome that also predisposes to renal cell cancer and brain tumors. Tuberous sclerosis is caused by germline inactivation of either TSC1 (9q34) or TSC2 (16p13.3), and the same tumor suppressor genes are inactivated somatically in sporadic PEComas.[138] Inactivation of either gene results in stimulation of the mTOR pathway, providing the basis for the treatment of nonsurgically curable tumors with similar genetic inactivation (lymphangioleiomyomatosis and angiomyolipoma) with mTOR inhibitors.[139,140] A small proportion of PEComas have TFE3 rearrangements with fusions involving various genes, including SFPQ and RAD51B.[141]
Most PEComas have a benign clinical course, but malignant behavior has been reported and can be predicted based on the size of the tumor, mitotic rate, and presence of necrosis.[142]
There are no standard treatment options. Treatment may include surgery or observation followed by surgery when the tumor is large.[143]
In tumors with evidence of mTORC1 activation and TSC1 or TSC2 loss, including lymphangioleiomyomatosis and angiomyolipoma,[139] clinical activity using mTOR inhibitors, such as sirolimus, has been well documented. In a small case series, three adult patients with PEComas responded to sirolimus.[144]
In a phase II trial, 34 patients with metastatic or locally advanced malignant PEComas were treated with sirolimus protein-bound particles for injectable suspension (albumin-bound) (nab-sirolimus). Of the 31 patients eligible for efficacy analysis, 12 (39%) had a response (1 complete response and 11 partial responses), 16 (52%) had stable disease, and 3 (10%) had progressive disease. Responses were rapid and durable. The median duration of response was not reached after a median follow-up of 2.5 years. Treatment was ongoing for 7 of 12 patients who responded to treatment (range, 5.6 months to longer than 47.2 months). Tumor variant profiling was completed for 25 specimens. Eight of nine patients with TSC2 variants responded to treatment, while only 2 of 16 patients without TSC2 variants responded. In addition, responses were noted in 10 of 17 patients with phospho-S6 (pS6) expression. No response was noted in eight patients without pS6 expression. The absence of pS6 expression reflects the lack of mTORC1 activation.[145][Level of evidence C1] In 2021, the FDA approved nab-sirolimus for adult patients with PEComas.
From 1972 to 2006, patients with undifferentiated soft tissue sarcoma were eligible for participation in rhabdomyosarcoma trials coordinated by the IRS group and the COG. The rationale was that patients with undifferentiated soft tissue sarcoma had sites of disease and outcomes that were similar to those in patients with alveolar rhabdomyosarcoma. Therapeutic trials for adults with soft tissue sarcoma include patients with undifferentiated soft tissue sarcoma and other histologies, which are treated similarly, using ifosfamide and doxorubicin, and sometimes with other chemotherapy agents, surgery, and radiation therapy.
In the COG ARST0332 (NCT00346164) trial, patients with high-grade undifferentiated sarcoma were treated with an ifosfamide- and doxorubicin-based regimen. Results for the patients with high-grade undifferentiated sarcoma were reported together with all high-grade soft tissue sarcomas in the trial. The estimated 5-year EFS rate was 64% and the OS rate was 77% for sarcomas classified as high grade by the Fédération Nationale des Centres de Lutte Contre Le Cancer (FNCLC).[5][Level of evidence C1]
In a report of 32 patients with undifferentiated soft tissue sarcomas who were enrolled on the ARST0332 (NCT00346164) trial, the median age at enrollment was 13.6 years, and two-thirds of the patients were male. The most common primary sites were the paraspinal region and extremities. Five patients presented with metastatic disease.[146]
At one time, malignant fibrous histiocytoma was the single most common histotype among adults with soft tissue sarcomas. Since it was first recognized in the early 1960s, malignant fibrous histiocytoma has been controversial, in terms of both its histogenesis and its validity as a clinico-pathological entity. The World Health Organization (WHO) classification no longer includes malignant fibrous histiocytoma as a distinct diagnostic category but rather as a subtype of an undifferentiated pleomorphic sarcoma.[147,148]
This entity accounts for 2% to 6% of all childhood soft tissue sarcomas.[149]
These tumors occur mainly in the second decade of life. In a series of ten patients, the median age was 10 years, and the tumor was most commonly located in the extremities. In this series, all tumors were localized, and five of nine patients (for whom follow-up was available) were alive and in first remission.[149]
In another series of 17 pediatric patients with malignant fibrous histiocytoma, the median age at diagnosis was 5 years and the extremities were involved in eight cases.[150] All patients with metastatic disease died, and two patients experienced a clinical response to a doxorubicin-based regimen.
For more information about the treatment of malignant fibrous histiocytoma of bone, see Osteosarcoma and Undifferentiated Pleomorphic Sarcoma of Bone Treatment.
These tumors can arise in previously irradiated sites or as a second malignancy in patients with retinoblastoma.[151]
An analysis of 70 patients who were diagnosed with malignant fibrous histiocytosis of no specific type, storiform or pleomorphic malignant fibrous histiocytoma, pleomorphic sarcoma, or undifferentiated pleomorphic sarcoma showed a highly complex karyotype with no specific recurrent aberrations.[152]
Undifferentiated sarcomas with 12q13–15 amplification, including MDM2 and CDK4, are best classified as dedifferentiated liposarcomas.[152] The relationship between this tumor and the family of undifferentiated/unclassified tumors with spindle cell morphology remains relatively undefined.
For information about the treatment of undifferentiated pleomorphic sarcoma of bone, see Osteosarcoma and Undifferentiated Pleomorphic Sarcoma of Bone Treatment.
Treatment options for recurrent or refractory pleomorphic sarcoma include the following:
The Sarcoma Alliance for Research through Collaboration conducted a phase II trial of the checkpoint inhibitor pembrolizumab in patients aged 18 years and older with recurrent soft tissue sarcoma.[153][Level of evidence C3]
See the sections on Undifferentiated Small Round Cell Sarcomas With BCOR Genetic Alterations and Genomics of Ewing Sarcoma in Ewing Sarcoma and Undifferentiated Small Round Cell Sarcomas of Bone and Soft Tissue Treatment.
See the sections on Undifferentiated Small Round Cell Sarcomas With CIC Genetic Alterations and Genomics of Ewing Sarcoma in Ewing Sarcoma and Undifferentiated Small Round Cell Sarcomas of Bone and Soft Tissue Treatment.
See the Undifferentiated Small Round Cell Sarcomas With EWSR1::non-ETS Fusions section in Ewing Sarcoma and Undifferentiated Small Round Cell Sarcomas of Bone and Soft Tissue Treatment.
Vascular tumors vary from hemangiomas, which are always considered benign, to angiosarcomas, which are highly malignant.[1] Malignant vascular tumors include the following subtypes:
Epithelioid hemangioendothelioma was first described in soft tissue by Weiss and Enzinger in 1982. These tumors can occur in younger patients, but the peak incidence is in the fourth and fifth decades of life. The number of pediatric patients reported in the literature is limited.
Epithelioid hemangioendotheliomas can have an indolent or very aggressive course, with an overall survival rate of 73% at 5 years. There are case reports of patients with untreated multiple lesions who have a very benign course. However, other patients have a very aggressive course. Some pathologists have tried to stratify patients to evaluate risks and adjust treatment, but more research is needed.[2-8]
A multi-institutional case series reported on 24 patients aged 2 to 26 years with epithelioid hemangioendotheliomas.[9][Level of evidence C2] Most patients presented with multiorgan disease. Progression was seen in 63% of patients, with a mean time to progression of 18.4 months (range, 0–72 months).
The presence of effusions, tumor size larger than 3 cm, and a high mitotic index (>3 mitoses/50 high-power fields) have been associated with unfavorable outcomes.[4]
Common sites of involvement are liver alone (21%), liver plus lung (18%), lung alone (12%), and bone alone (14%).[4,10,11] Clinical presentation depends on the site of involvement, as follows:
WWTR1::CAMTA1 gene fusions have been found in most patients. Less commonly, YAP1::TFE3 gene fusions have been reported.[2] These gene fusions are not directly targetable with current medications. Monoclonality has been described in multiple liver lesions, suggesting a metastatic process.
Histologically, these lesions are characterized as epithelioid lesions arranged in nests, strands, and trabecular patterns, with infrequent vascular spaces. Features that may be associated with aggressive clinical behavior include cellular atypia, one or more mitoses per 10 high-power fields, an increased proportion of spindled cells, focal necrosis, and metaplastic bone formation.[4]
Treatment options for epithelioid hemangioendothelioma include the following:
For indolent cases, observation is warranted. Surgery is performed when resection is possible. Liver transplant has been used with aggressive liver lesions, both with and without metastases.[4,12-14]
For more aggressive cases, several different drugs have been used, including interferon, thalidomide, sorafenib, pazopanib, and sirolimus.[12,15,16] The most aggressive cases are treated with angiosarcoma-type chemotherapy.
A multi-institutional case series reported on 24 patients aged 2 to 26 years with epithelioid hemangioendothelioma.[9][Level of evidence C2]
A report from 2020 that investigated sirolimus treatment in children aimed to add to the previous experience of sirolimus in adults. A retrospective review identified six pediatric patients with disseminated epithelioid hemangioendothelioma who were treated with sirolimus.[17]
A report from the European Soft Tissue Sarcoma study group analyzed ten patients with localized disease and one patient with metastatic disease from two studies.[18] The median age was 14.3 years (range, 9.0–18.8 years). Local therapy was initial primary surgery in seven patients, and five patients received systemic therapy. No patients received radiation therapy.
Patients or families who desire additional disease-directed therapy should consider entering trials of novel therapeutic approaches because no standard agents have demonstrated clinically significant activity.
Regardless of whether a decision is made to pursue disease-directed therapy at the time of progression, palliative care remains a central focus of management. This ensures that quality of life is maximized while attempting to reduce symptoms and stress related to the terminal illness.
Information about National Cancer Institute (NCI)–supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.
Use our advanced clinical trial search to find NCI-supported cancer clinical trials that are now enrolling patients. The search can be narrowed by location of the trial, type of treatment, name of the drug, and other criteria. General information about clinical trials is also available.
Angiosarcomas are rare (accounting for 2% of sarcomas), aggressive, vascular tumors that can arise in any part of the body but is more common in soft tissues. Angiosarcoma has an estimated incidence of 2 cases per 1 million people. In the United States, it affects approximately 600 people annually, who are typically aged 60 to 70 years.[19]
Angiosarcomas are extremely rare in children. It is unclear if the pathophysiology of angiosarcomas in children differs from that of angiosarcomas in adults. Cases have been reported in neonates and toddlers, with presentation of multiple cutaneous lesions and liver lesions, some of which are GLUT1 positive.[20-23] Most angiosarcomas involve the skin and superficial soft tissue, although the liver, spleen, and lung can be affected; bone is rarely affected.
Nomenclature of these liver lesions has been difficult and confusing with use of outdated terminology proposed in 1971 (e.g., type I hemangioendothelioma: infantile hemangioma; type II hemangioendothelioma: low-grade angiosarcoma; type III hemangioendothelioma: high-grade angiosarcoma).[21] A report of eight cases of liver angiosarcomas in children highlighted the misuse of the term hemangioendothelioma and the importance of early diagnosis and treatment of these tumors.[24]
Established risk factors include the following:[25]
Angiosarcomas are largely aneuploid tumors. The rare cases of angiosarcoma that arise from benign lesions such as hemangiomas have a distinct pathway that needs to be investigated. MYC amplification is seen in radiation-induced angiosarcoma. KDR variants and FLT4 amplifications have been seen with a frequency of less than 50%.[25]
Histopathological diagnosis can be very difficult because there can be areas of varied atypia. A common feature of angiosarcoma is an irregular network of channels in a dissective pattern along dermal collagen bundles. There is varied cellular shape, size, mitosis, endothelial multilayering, and papillary formation. Epithelioid cells can also be present. Necrosis and hemorrhage are common. Tumors stain for factor VIII, CD31, and CD34. Some liver lesions can mimic infantile hemangiomas and have focal GLUT1 positivity.[21]
Treatment options for angiosarcoma include the following:
Localized disease can be cured by aggressive surgery. Complete surgical excision appears to be crucial for the long-term survival of patients with angiosarcomas and lymphangiosarcomas, despite evidence of tumor shrinkage in some patients who were treated with local or systemic therapy.[22,26-28] Data on liver transplant for localized angiosarcomas are limited.[29][Level of evidence C1]
Evidence (surgery):
Localized disease, especially cutaneous angiosarcomas, can be treated with radiation therapy or combined chemotherapy (e.g., paclitaxel) and radiation therapy.[31] Most of these reported cases are in adults.[32] When radiation is used, the doses are high (50–70 Gy), the cutaneous volumes are extensive because of the infiltrating nature of the disease, and regional (draining) nodes are often included, even if clinically negative.[33,34] Because of these factors, radiation therapy is rarely used to treat children.
Multimodal treatment with surgery, systemic chemotherapy, and radiation therapy is used for metastatic disease, although it is rarely curative.[34,35] Disease control is the objective in patients with metastatic angiosarcomas. Published progression-free survival is between 3 months and 7 months,[36] and the median overall survival (OS) is 14 to 18 months.[37] In both adults and children, the 5-year OS rates are between 20% and 35%.[22,23,38]
One child who was diagnosed with angiosarcoma secondary to malignant transformation from infantile hemangioma responded to treatment with bevacizumab (a monoclonal antibody against vascular endothelial growth factor) combined with systemic chemotherapy.[20,35]
Biologic agents that inhibit angiogenesis have shown activity in adults with angiosarcomas.[21,38]
There is one case report of a pediatric patient with metastatic cardiac angiosarcoma who was successfully treated with conventional chemotherapy, radiation, surgery, and targeted therapies, including pazopanib.[39]
Regardless of whether a decision is made to pursue disease-directed therapy at the time of progression, palliative care remains a central focus of management. This ensures that quality of life is maximized while attempting to reduce symptoms and stress related to the terminal illness.
Patients or families who desire additional disease-directed therapy should consider entering trials of novel therapeutic approaches because no standard agents have demonstrated clinically significant activity.
Information about National Cancer Institute (NCI)–supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.
Use our advanced clinical trial search to find NCI-supported cancer clinical trials that are now enrolling patients. The search can be narrowed by location of the trial, type of treatment, name of the drug, and other criteria. General information about clinical trials is also available.
Standard treatment options for metastatic childhood soft tissue sarcoma include the following:
For treatment options, see the individual tumor type sections of the summary.
The prognosis for children with metastatic soft tissue sarcomas is poor.[1-6] These children should receive combined treatment with chemotherapy, radiation therapy, and surgical resection of pulmonary metastases. In a prospective randomized trial, chemotherapy with vincristine, dactinomycin, doxorubicin, and cyclophosphamide, with or without dacarbazine, led to tumor responses in one-third of patients with unresectable or metastatic disease. However, the estimated 4-year survival rate was poor. Less than one-third of children survived.[6-8]
Targeted (stereotactic body) radiation therapy is an option for sites of metastasis, particularly the lung.[9] Targeted radiation therapy is also an option for local control or sites of metastasis, including the lungs, bones, and brain,[10,11] particularly in patients for whom the morbidity of resection is a concern or whose life expectancy is limited.[9]
In a prospective trial of children with metastatic soft tissue sarcoma, patients were randomly assigned to receive multiagent chemotherapy with or without the addition of bevacizumab.[12] There was no difference in event-free survival or overall survival between the two study arms.
Generally, a surgical procedure, with resection of all gross disease, should be considered for children with isolated pulmonary metastases.[13] For patients with multiple or recurrent pulmonary metastases, additional surgical procedures can be performed if the morbidity is deemed acceptable. In a retrospective review, patients with synovial sarcoma and pulmonary metastases who underwent complete resection of all metastatic lung lesions had better survival than did patients who did not undergo complete resections.[13][Level of evidence C1] Formal segmentectomy, lobectomy, and mediastinal lymph node dissection are unnecessary.[14]
An alternative approach is focused radiation therapy (fractionated stereotactic radiation therapy), which has been successfully used in adults to control lesions. The estimated 5-year survival rate after thoracotomy for pulmonary metastasectomy has ranged from 10% to 58% in adult studies.[9]
With the possible exception of infants with infantile fibrosarcoma, the prognosis for patients with progressive or recurrent disease is poor. No prospective trial has demonstrated that enhanced local control of pediatric soft tissue sarcomas will ultimately improve survival. Therefore, treatment should be individualized for the site of recurrence, biological characteristics of the tumor (e.g., grade, invasiveness, and size), previous therapies, and individual patient considerations. All patients with recurrent tumors should consider participating in clinical trials.
Published results of two studies addressed the outcomes of children with relapsed synovial sarcoma. Most patients in one study had distant relapse (29 of 44 patients),[1] while most patients in the second study had local relapse (27 of 37 patients).[2] Distant recurrence was a poor prognostic variable, while tumor resectability at relapse (as manifested by extremity recurrence) was associated with a better outcome in both studies.
Resection is the standard treatment for recurrent pediatric nonrhabdomyosarcomatous soft tissue sarcomas. If the patient has not yet received radiation therapy, postoperative radiation should be considered after local excision of the recurrent tumor. Limb-sparing procedures with postoperative brachytherapy have been evaluated in adults but have not been studied extensively in children. For some children with extremity sarcomas who have received previous radiation therapy, amputation may be the only therapeutic option.
Treatment options for progressive or recurrent disease include the following:
Evidence (surgery):
Chemotherapy agents that have been used to treat recurrent soft tissue sarcomas include the following:
Evidence (tyrosine kinase inhibitors):
Evidence (immune checkpoint inhibitors):
Information about National Cancer Institute (NCI)–supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.
Use our advanced clinical trial search to find NCI-supported cancer clinical trials that are now enrolling patients. The search can be narrowed by location of the trial, type of treatment, name of the drug, and other criteria. General information about clinical trials is also available.
The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
Treatment of Fibroblastic and Myofibroblastic Tumors
Added text about the results of a retrospective, international, multicenter study that analyzed patients younger than 21 years with ROS1-altered inflammatory myofibroblastic tumors who were enrolled in either the European paediatric Soft Tissue Sarcoma Study Group NRSTS-2005 study or the Soft Tissue Sarcoma Registry (cited Schoot et al. as reference 70).
Treatment of Peripheral Nerve Sheath Tumors
Added text to state that most malignant triton tumors are reported in adults, although they may also arise in children and adolescents (cited de Traux de Wardin et al. as reference 26).
Added text to state that distinguishing between malignant triton tumors and NF1-altered rhabdomyosarcomas can be difficult. The genomic characteristics of malignant triton tumors can aid in differentiating between the two tumors. CDKN2A deep deletions and loss-of-function alterations in genes of the PRC2 complex are commonly observed in malignant triton tumors, while they are uncommon in NF1-altered rhabdomyosarcomas. The loss of PRC2 function leads to loss of H3K27me3 expression, a finding that is common in malignant triton tumors. H3K27me3 expression is generally maintained in rhabdomyosarcomas (cited Schaefer et al. and Hornick et al. as references 27 and 28, respectively).
This summary is written and maintained by the PDQ Pediatric Treatment Editorial Board, which is editorially independent of NCI. The summary reflects an independent review of the literature and does not represent a policy statement of NCI or NIH. More information about summary policies and the role of the PDQ Editorial Boards in maintaining the PDQ summaries can be found on the About This PDQ Summary and PDQ® Cancer Information for Health Professionals pages.
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the treatment of childhood soft tissue sarcoma. It is intended as a resource to inform and assist clinicians in the care of their patients. It does not provide formal guidelines or recommendations for making health care decisions.
This summary is reviewed regularly and updated as necessary by the PDQ Pediatric Treatment Editorial Board, which is editorially independent of the National Cancer Institute (NCI). The summary reflects an independent review of the literature and does not represent a policy statement of NCI or the National Institutes of Health (NIH).
Board members review recently published articles each month to determine whether an article should:
Changes to the summaries are made through a consensus process in which Board members evaluate the strength of the evidence in the published articles and determine how the article should be included in the summary.
The lead reviewers for Childhood Soft Tissue Sarcoma Treatment are:
Any comments or questions about the summary content should be submitted to Cancer.gov through the NCI website's Email Us. Do not contact the individual Board Members with questions or comments about the summaries. Board members will not respond to individual inquiries.
Some of the reference citations in this summary are accompanied by a level-of-evidence designation. These designations are intended to help readers assess the strength of the evidence supporting the use of specific interventions or approaches. The PDQ Pediatric Treatment Editorial Board uses a formal evidence ranking system in developing its level-of-evidence designations.
PDQ is a registered trademark. Although the content of PDQ documents can be used freely as text, it cannot be identified as an NCI PDQ cancer information summary unless it is presented in its entirety and is regularly updated. However, an author would be permitted to write a sentence such as “NCI’s PDQ cancer information summary about breast cancer prevention states the risks succinctly: [include excerpt from the summary].”
The preferred citation for this PDQ summary is:
PDQ® Pediatric Treatment Editorial Board. PDQ Childhood Soft Tissue Sarcoma Treatment. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/types/soft-tissue-sarcoma/hp/child-soft-tissue-treatment-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389361]
Images in this summary are used with permission of the author(s), artist, and/or publisher for use within the PDQ summaries only. Permission to use images outside the context of PDQ information must be obtained from the owner(s) and cannot be granted by the National Cancer Institute. Information about using the illustrations in this summary, along with many other cancer-related images, is available in Visuals Online, a collection of over 2,000 scientific images.
Based on the strength of the available evidence, treatment options may be described as either “standard” or “under clinical evaluation.” These classifications should not be used as a basis for insurance reimbursement determinations. More information on insurance coverage is available on Cancer.gov on the Managing Cancer Care page.
More information about contacting us or receiving help with the Cancer.gov website can be found on our Contact Us for Help page. Questions can also be submitted to Cancer.gov through the website’s Email Us.