Primary brain tumors, including germ cell tumors (GCTs), are a diverse group of diseases that together constitute the most common solid tumors of childhood. The most recent World Health Organization (WHO) Classification of Central Nervous System Tumours implements some molecular parameters, in addition to histology, to define brain tumor entities.[1,2] Some CNS tumor types, such as embryonal tumors and gliomas, are organized according to molecular characterization. However, this updated classification schema does not yet categorize intracranial GCTs using molecular parameters. Tumor location, extent of disease (brain invasion and tumor spread), and type of CNS GCT histology remain important factors that affect treatment and prognosis.
CNS GCTs are broadly classified as germinomatous (commonly referred to as germinoma) and nongerminomatous germ cell tumors (NGGCTs) on the basis of clinicopathological and laboratory features, including tumor markers.[2,3] An alternative therapeutic classification in Japan distinguishes three groups on the basis of their prognosis: good prognosis (e.g., germinoma), intermediate prognosis (e.g., immature teratoma with malignant transformation), and poor prognosis (e.g., yolk sac tumor, choriocarcinoma, embryonal carcinoma, and mixed tumors of those entities).[3]
The PDQ childhood brain tumor treatment summaries are organized primarily according to the WHO Classification of Central Nervous System Tumours.[1-3] For a full description of the classification of CNS tumors and a link to the corresponding treatment summary for each type of brain tumor, see the Childhood Brain and Spinal Cord Tumors Summary Index.
In Western countries, GCTs represent 3% to 4% of primary brain tumors in children, with a peak incidence from age 10 to 19 years.[4,5] In Japan and other Asian countries, a series reported the incidence of CNS GCTs to be approximately 15% of all pediatric CNS tumors.[5-9] The genetic or environmental reasons for these differences remain unknown.
Overall, males have a higher incidence of GCTs than females. Male patients have a preponderance of pineal-region primary tumors.[10,11] However, male predominance is not noted in patients aged 10 years or younger at the time of diagnosis.[12]
CNS GCTs usually arise in the pineal and/or suprasellar regions of the brain as solitary or multiple lesions (see Figure 1). The most common site of origin is the pineal region (45%), and the second most common site is the suprasellar region (30%) within the infundibulum or pituitary stalk. Both of these sites are considered extra-axial or nonparenchymal CNS locations. Approximately 5% to 10% of patients present with synchronous tumors arising in both the suprasellar and pineal locations. Germinoma is the most frequently observed histology.[8] Other sites that may be involved include the basal ganglia, thalamus, and, less frequently, the ventricles, cerebral hemispheres, and brain stem.[10,11,13] Suprasellar tumors are most common in younger patients, whereas pineal or bifocal presentation predominates in older patients.[12]
The signs and symptoms of CNS GCTs depend on the location of the tumor in the brain, as follows:
Nonspecific symptoms such as enuresis, anorexia, and psychiatric complaints [17] can lead to delays in a diagnosis. However, signs of increased intracranial pressure or visual changes tend to result in an earlier diagnosis.[18]
Radiographic characteristics of CNS GCTs cannot reliably differentiate germinomas from NGGCTs or other CNS tumors. The diagnosis of GCTs is based on the following:
The diagnosis of a suspected CNS GCT and an assessment of the clinical deficits and extent of metastases can usually be confirmed with the following tests:
If possible, a baseline neuropsychological examination should be performed after symptoms of endocrine deficiency and raised intracranial pressure are resolved.
CNS GCTs can be diagnosed and classified on the basis of histology alone, tumor markers alone, or a combination of both.[19-21] A diagnosis of GCTs often requires a tumor biopsy, except when imaging characteristics are present and increased tumor markers (usually AFP and beta-HCG) are found in the serum and/or CSF. The tumor markers AFP and beta-HCG are the most useful, although other markers, such as placental alkaline phosphatase and c-kit, are being investigated (see Table 1). When the tumor markers are negative or mildly elevated but below diagnostic criteria, or if there are any atypical findings, an endoscopic or open biopsy is needed to make a definitive diagnosis.
Distinguishing between different GCT types by CSF protein marker levels alone is somewhat arbitrary, and standards vary across continents. Patients with pure germinomas and teratomas usually present with negative markers, but low levels of beta-HCG can be detected in patients with germinomas.[22] Current international efforts are directed at determining a marker threshold for beta-HCG–secreting germinomas because data suggest that the beta-HCG levels that are used to distinguish germinomas from NGGCTs (50 IU/L in Europe and 100 IU/L in North America) are questionable.
The use of tumor markers and histology in GCT clinical trials is evolving. For example, in the COG-ACNS1123 (NCT01602666) trial, patients were eligible for assignment to the germinoma regimen without biopsy confirmation if they had one of the following:
Tumor Type | Beta-HCG | AFP | PLAP | c-kit | |
---|---|---|---|---|---|
AFP = alpha-fetoprotein; HCG = human chorionic gonadotropin; PLAP = placental alkaline phosphatase; + = positive; +++ = highly positive (elevated); - = negative; ± = equivocal. | |||||
Germinoma | ± | - | ± | + | |
Germinoma (syncytiotrophoblastic) | + | - | ± | + | |
Embryonal carcinoma | ± | + | ± | - | |
Yolk sac tumor | - | +++ | ± | - | |
Choriocarcinoma | +++ | - | ± | - | |
Teratoma | |||||
Immature teratoma | ± | ± | - | ± | |
Immature teratoma with malignant components | ± | + | + | ± | |
Mature teratoma | - | - | - | - | |
Mixed germ cell tumor | ± | ± | ± | ± |
There is also an effort to use tumor markers to determine prognosis on the basis of the presence and degree of elevation of AFP and beta-HCG. This is an evolving process, and cooperative groups in North America, Europe, and Japan have adopted slightly different criteria.[23]
Alternative classification schemes for CNS GCTs have been proposed by groups such as the Japanese Pediatric Brain Tumor Study Group for CNS GCTs. This group based their stratification on the prognostic grouping of the differing histological variants, as shown in Table 2.[9]
Prognostic Group | Tumor Type |
---|---|
Good | Germinoma, pure |
Mature teratoma | |
Intermediate | Germinoma with syncytiotrophoblastic giant cells |
Immature teratoma | |
Mixed tumors mainly composed of germinoma or teratoma | |
Teratoma with malignant transformation | |
Poor | Choriocarcinoma |
Embryonal carcinoma | |
Mixed tumors mainly composed of choriocarcinoma, yolk sac tumor, or embryonal carcinoma | |
Yolk sac tumor |
It is crucial that appropriate staging is determined and that germinomas are distinguished from NGGCTs. Chemotherapy and radiation treatment plans differ significantly depending on GCT category and extent of disease.
The pathogenesis of intracranial GCTs is unknown. The germ cell theory proposes that CNS GCTs arise from primordial germ cells that have aberrantly migrated and undergone malignant transformation. A genome-wide methylation profiling study of 61 GCTs supports this hypothesis.[24] Previous molecular studies that compared the genomic alterations in GCTs showed similar copy-number alterations in both CNS GCTs and systemic GCTs.[25]
An alternative hypothesis, the embryonic cell theory, proposes that GCTs arise from a pluripotent embryonic cell that escapes normal developmental signals and progresses to CNS GCTs.[26,27]
The WHO has classified CNS GCTs into the following groups:[1,2]
NGGCTs can consist of one malignant NGGCT type or contain multiple elements of GCT components, including teratomatous or germinomatous constituents.
Recurrent variants in KIT, genes in the MAPK pathway, and genes in the PI3K/mTOR signaling pathway have been identified in CNS GCTs.[28-30]
In a retrospective analysis of 82 children and adults with CNS GCTs, chromosome 12p gain was the most frequent copy number alteration. 12p gain was more frequent in NGGCTs (20 of 40, 50%) than germinomas (5 of 42, 12%). 12p gain was associated with worse survival in patients with NGGCTs (10-year overall survival rate, 47% for patients with 12p gain vs. 90% without; P = .02).[31]
Global hypomethylation that mirrors primordial germ cells in early development has also been observed in CNS GCTs.[30]
In an evaluation of 21 cases of CNS germinomas diagnosed between 2000 and 2016, programmed death-ligand 1 (PD-L1) and programmed cell death-1 (PD-1) expression was assessed by immunohistochemistry. Ninety percent of germinomas had germ cell components that stained positively for PD-L1. In addition, tumor-associated lymphocytes stained positive for PD-L1 in more than 75% of cases.[32]
There is no universally accepted clinical staging system for germ cell tumors (GCTs), but a modified Chang staging system has traditionally been used.[1] Staging evaluation of central nervous system (CNS) GCTs includes the following:
Ventricular tumor markers are obtained for AFP and beta-HCG in the presence of obstructive hydrocephalus and a necessary CSF diversion. However, ventricular CSF does not serve as a substitute for CSF tumor staging and cytopathological review. Both serum and CSF tumor markers should be obtained for a thorough staging and diagnostic evaluation.[2]
Patients with localized disease and negative CSF cytology are considered to be metastatic negative (M0). Patients with positive CSF cytology or patients with drop metastasis (spinal or cranial subarachnoid metastases) are considered to be metastatic positive (M+). Appropriate staging is crucial because patients with metastatic disease require extended radiation fields.
GCTs may be disseminated throughout the neuraxis at the time of diagnosis or at any disease stage. Several patterns of spread may occur in germinomas, such as subependymal dissemination in the lateral or third ventricles and parenchymal infiltration. Extracranial spread to lung or bone is rare but has been reported.[3,4]
Teratomas, germinomas, and other nongerminomatous germ cell tumors (NGGCTs) have differing prognoses and require different treatment regimens. Studies have observed the following:[1-5]
Table 3 outlines the treatment options for patients with newly diagnosed and recurrent childhood CNS GCTs.
Treatment Group | Treatment Options | |
---|---|---|
Newly diagnosed childhood CNS germinomas | Neoadjuvant chemotherapy followed by response-based radiation therapy | |
Radiation therapy | ||
Newly diagnosed childhood CNS nongerminomatous GCTs | Chemotherapy followed by radiation therapy | |
Surgery, if incomplete response to chemotherapy before irradiation | ||
Newly diagnosed childhood CNS teratomas | Gross-total resection | |
Recurrent childhood CNS GCTs | Chemotherapy followed by additional radiation therapy | |
High-dose chemotherapy with stem cell rescue with or without additional radiation therapy |
Dramatic improvements in survival have been achieved for children and adolescents with cancer. Between 1975 and 2010, childhood cancer mortality decreased by more than 50%.[9] Childhood and adolescent cancer survivors require close monitoring because side effects of cancer therapy 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.
Treatment options for newly diagnosed childhood central nervous system (CNS) germinomas include the following:
Chemotherapy has been explored to reduce radiation therapy doses and associated neurodevelopmental morbidity. Several studies have confirmed the feasibility of this approach for maintaining excellent survival rates.[1-4][Level of evidence B4]; [5-8][Level of evidence C1]
Chemotherapy agents such as cyclophosphamide, ifosfamide, etoposide, cisplatin, and carboplatin are highly active in CNS germinomas. Managing patients receiving chemotherapy agents that require hyperhydration (e.g., cyclophosphamide, ifosfamide, and cisplatin) can be quite challenging because of the possibility of diabetes insipidus in patients with primary tumors of the suprasellar region.[9]
An international group of investigators explored a chemotherapy-only approach primarily for younger children. A complete response was achieved in 84% of patients with germinomas who were treated with chemotherapy alone. However, 50% of these patients suffered tumor relapse or progression. Many recurrences were local, local plus ventricular, and ventricular alone and/or with leptomeningeal dissemination throughout the CNS, which required additional therapy, including radiation.[10]
Subsequent studies have continued to support the need for radiation therapy after chemotherapy and the likely requirement for whole-ventricular irradiation (24 Gy) with local tumor site–boost radiation therapy (total dose, 40 Gy).[11][Level of evidence B4]; [12][Level of evidence C1] Excellent results have also been reported for patients with metastatic germinomas who received craniospinal irradiation of 24 Gy with local tumor site–boost radiation therapy (total dose, 40 Gy).[1][Level of evidence B4]; [13]
Optimal management of bifocal lesions is less clear, but most investigators consider this presentation a form of metachronous primary disease to be staged as M0. A meta-analysis of 60 patients demonstrated excellent progression-free survival after craniospinal irradiation alone. Chemotherapy plus localized radiation therapy, including whole-ventricular irradiation, also resulted in excellent disease control.[14][Level of evidence C2] For germinomas that arise outside of the pineal or suprasellar region, the effectiveness of therapy, as used for pineal and/or suprasellar lesions, is not well delineated. However, one retrospective review of 47 patients with basal ganglion and thalamic tumors reported progression-free survival (PFS) and overall survival (OS) rates that were similar to those reported in patients with tumors arising in more common areas of the brain.[15]
Results have been reported for the ACNS1123 (NCT01602666) phase II trial (stratum 2) that investigated response-based radiation therapy for localized germinomas. Patients were aged 3 to 21 years. Patients who had a complete response to carboplatin and etoposide chemotherapy received 18 Gy of whole-ventricle irradiation and a 12-Gy boost to the tumor bed. Patients who had a partial response to chemotherapy proceeded to receive 24 Gy of whole-ventricle irradiation and a 12-Gy boost to the tumor bed. Longitudinal cognitive functioning was evaluated prospectively. There were 137 eligible patients. Among 90 evaluable patients, 74 were treated with 18 Gy of radiation, and 16 were treated with 24 Gy of whole-ventricle irradiation.[16]
Other studies have supported this treatment approach, reporting excellent outcomes in children with CNS germinomas.[17,18]
CNS germinomas are highly radiosensitive and have been traditionally treated successfully with radiation therapy alone. Historically, patients with nondisseminated disease have been treated with craniospinal irradiation plus a boost to the region of the primary tumor. The dose of craniospinal irradiation has ranged from 24 Gy to 36 Gy, although studies have used lower doses. The local tumor dose of radiation therapy has ranged between 40 Gy and 50 Gy. Studies of lower-dose craniospinal irradiation have shown excellent outcomes.[19] This modification has resulted in 5-year OS rates exceeding 90%.[20]; [21][Level of evidence B4]; [22,23][Level of evidence C1] These excellent survival rates have allowed investigators to focus on reducing the radiation treatment volume and dose in an attempt to decrease late effects.[21,24,25]
Patterns of relapse after craniospinal irradiation versus reduced-volume radiation therapy (whole-brain or whole-ventricular radiation therapy) have supported the omission of craniospinal irradiation for localized germinomas.[26-28] On the basis of these results, the treatment for patients with localized germinomas has been modified to cover the whole ventricular system (24 Gy) followed by a boost to the primary site (30–40 Gy), rather than to deliver radiation therapy to the entire craniospinal axis or even to the whole brain. This change has not resulted in worse outcomes and is expected to minimize the acute and long-term toxicity of radiation therapy. Focal radiation therapy directed only to the tumor volume, even after neoadjuvant chemotherapy, results in ventricular relapses; therefore, focal radiation therapy is not recommended.[25]
Early-phase therapeutic trials may be available for selected patients. These trials may be available via the Children’s Oncology Group, the Pediatric Brain Tumor Consortium, or other entities. 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.
Treatment options for newly diagnosed childhood central nervous system (CNS) nongerminomatous germ cell tumors (NGGCTs) include the following:
The optimal treatment regimen for CNS NGGCTs remains unclear.
The prognosis for children with CNS NGGCTs is inferior to that for children with germinomas, but the difference is diminishing with the addition of multimodality therapy. NGGCTs are radiosensitive, but patient survival rates after standard craniospinal irradiation alone has been poor, ranging from 20% to 45% at 5 years.[1] With the current treatment regimens, the 3-year to 5-year overall survival (OS) rates for patients with NGGCTs range from 75% to 90%.[2-4] In patients with NGGCTs who suffer tumor relapses, most occur within 3 years of diagnosis.[2]
The use of chemotherapy before radiation therapy has increased survival rates. However, the specific chemotherapy regimen, length of therapy, and the optimal radiation field, timing, and dose remain under investigation.[1,5,6] Anticancer agents that have been used include carboplatin, etoposide, bleomycin, ifosfamide, and vinblastine in different combinations. Some investigators have proposed radiation therapy fields that are smaller than those used for craniospinal irradiation (e.g., whole-ventricular irradiation with a boost to the local tumor site) for patients with nondisseminated NGGCT. Controversy exists over the pattern of tumor relapse in patients treated with chemotherapy and focal or whole-ventricular radiation therapy.[1,7-9]
Evidence (chemotherapy followed by radiation therapy):
Patients in this study received six cycles of chemotherapy with carboplatin and etoposide alternating with ifosfamide and etoposide. If a CR or PR with or without second-look surgery was achieved, the patient was eligible for reduced radiation therapy, defined as 30.6 Gy to the whole-ventricular field and a 54-Gy boost to the tumor bed, compared with 36 Gy of craniospinal irradiation plus a 54-Gy tumor-bed boost used in the ACNS0122 trial.[4,10]
The current and prevailing controversy in the management of patients with newly diagnosed, localized NGGCTs—who have no evidence of dissemination and either a complete radiographic response to chemotherapy or have no evidence of disease before and after the initiation of chemotherapy—is the radiation volume. The SIOP-CNS-GCT-96 (NCT00293358) trial employed involved fields of radiation only for these patients with no radiographic evidence of residual or disseminated disease. Two COG protocols used either craniospinal or whole-ventricular fields of radiation plus a boost to the primary tumor. The incidence of isolated spinal relapses was similar in all of these studies, ranging from 8% to 11%.
Patients with relapsed NGGCTs are difficult to treat with curative intent, and their prognosis is guarded. Whether craniospinal irradiation or whole-ventricular plus spinal radiation should be included for all newly diagnosed NGGCT patients is an unresolved controversy and a major question for future clinical trials.
A small percentage of patients treated with chemotherapy may have normalization of tumor markers with a less-than-complete radiographic response. Occasionally, a mass continues to expand in size even though tumor markers may have normalized. This condition, designated as growing teratoma syndrome, represents an accelerated growth of the mature teratoma components during or after treatment.[2,12-14] In such circumstances, complete surgical resection is the treatment of choice, as it provides histological confirmation and exclusion of mixed germ cell tumor components.
A SIOP trial identified a significant OS advantage for patients without residual disease (5-year PFS rate, 85% ± 0.04% vs. 48% ± 0.07%), which underscores the important role of second-look surgery after chemotherapy and before irradiation.[3]
A second-look surgery can help determine whether the residual mass contains teratoma, fibrosis, or residual NGGCT.[7,15] If second-look surgery finds mature teratoma or fibrosis after chemotherapy, the general approach is to proceed with radiation therapy as if the patient had achieved a CR to chemotherapy. However, if an active tumor is observed, then alternative treatment approaches are generally considered.[2]
Early-phase therapeutic trials may be available for selected patients. These trials may be available via the COG, the Pediatric Brain Tumor Consortium, or other entities. 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:
Teratomas are designated as mature or immature on the basis of the absence or presence of differentiated tissues. The Japanese Pediatric Brain Tumor Study Group stratifies teratomas for classification and intensity of treatment (chemotherapy and radiation) into a good-prognosis group (mature teratomas) and an intermediate-prognosis group (immature teratomas) (see Table 2), while the Children’s Oncology Group includes immature teratomas with other nongerminomatous germ cell tumors.
Treatment options for newly diagnosed childhood central nervous system (CNS) teratomas include the following:
The primary treatment for teratomas is gross-total resection.[1,2][Level of evidence C1]
Adjuvant treatment in the form of focal radiation therapy and/or adjuvant chemotherapy for patients with subtotally resected tumors is controversial. Small institutional series suggested a potential utility of stereotactic radiosurgery.[1,2][Level of evidence C1]
Treatment options for recurrent childhood central nervous system (CNS) germ cell tumors (GCTs) include the following:
For patients who had localized germinomas at diagnosis and were treated with craniospinal and local boost radiation therapy, the most common form of relapse is at the primary site.[1] In contrast, the site of relapse is more variable in patients who relapse after chemotherapy and focal radiation therapy with or without whole-ventricular radiation to the primary site of disease. These patients have different combinations of local, disseminated ventricular, cerebral, leptomeningeal, and spinal relapse.[1,2]
Patients with disseminated germinomas and nongerminomatous germ cell tumors (NGGCTs) also may have complex patterns of relapse, including local and/or disseminated intracranial or intraspinal relapse after treatment with craniospinal radiation therapy alone or preirradiation chemotherapy with various volumes and doses of radiation therapy.[1-3]
Enrollment on clinical trials should be considered for all patients with recurrent disease. Information about ongoing National Cancer Institute (NCI)–supported clinical trials is available from the NCI website.
Patients with germinomas that were treated initially with chemotherapy only can benefit from chemotherapy followed by radiation therapy at the time of relapse.[4,5] Reirradiation, including radiosurgery, after chemotherapy at recurrence has been used.[5-9]
For patients with pure germinomas who previously received radiation therapy, myeloablative chemotherapy with stem cell rescue has been used. High-dose chemotherapy and autologous stem cell rescue may also have curative potential for some patients with relapsed systemic NGGCTs.[7,9-13]
There are limited clinical trials available for patients with recurrent NGGCTs. Early-phase therapeutic trials may be available for selected patients. These trials may be available via the Children’s Oncology Group (COG), the Pediatric Brain Tumor Consortium, or other entities. 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.
A significant proportion of children with central nervous system (CNS) germ cell tumors (GCTs) present with endocrinopathies, including diabetes insipidus and panhypopituitarism. In most cases, these endocrinopathies are permanent despite tumor control, and patients will need continuous hormone replacement therapy.[1,2]
Although significant improvements in the overall survival of patients with CNS GCTs have occurred, patients face significant late effects based on the location of the primary tumor and its treatment. These sequelae are not only limited to children, but they can also occur in adolescents and young adults. Treatment-related late effects include the following:
Current clinical trials and therapeutic approaches are directed at minimizing the long-term sequelae that result from the treatment of CNS GCTs.
For information about the incidence, type, and monitoring of late effects in survivors of childhood and adolescent cancer, see Late Effects of Treatment for Childhood Cancer.
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 Newly Diagnosed Childhood Central Nervous System (CNS) Germinomas
Added text to state that other studies have supported the treatment approach of chemotherapy and response-based radiation therapy, reporting excellent outcomes in children with CNS germinomas (cited Cappellano et al. as reference 17).
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This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the treatment of childhood central nervous system germ cell tumors. 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.
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PDQ® Pediatric Treatment Editorial Board. PDQ Childhood Central Nervous System Germ Cell Tumors Treatment. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/types/brain/hp/child-cns-germ-cell-treatment-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389498]
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