Primary brain tumors, including gliomas, are a diverse group of diseases that together constitute the most common solid tumors of childhood. Brain tumors are classified according to histology and molecular features, but tumor location and extent of spread are also important factors that affect treatment and prognosis. Histological features, immunohistochemical analysis, and cytogenetic and molecular genetic findings are used in tumor diagnosis and classification.
Gliomas are thought to arise from neural stem and progenitor cells that are present in the brain and spinal cord. Gliomas are classified on the basis of histological and molecular features, and they represent the most common type of central nervous system (CNS) tumor in children.
Historically, pediatric gliomas were classified into low-grade (World Health Organization [WHO] grades 1–2) and high-grade (WHO grades 3–4) gliomas on the basis of histological features. However, the incorporation of molecular biomarkers has led to a new classification scheme. According to the 2021 WHO Classification of Tumours: Central Nervous System Tumours (5th edition), gliomas, glioneuronal tumors, and neuronal tumors are broadly classified into adult-type diffuse gliomas, pediatric-type diffuse low-grade gliomas, pediatric-type diffuse high-grade gliomas, circumscribed astrocytic gliomas, glioneuronal and neuronal tumors, and ependymal tumors.[1,2] Within these tumor types, various subtypes are recognized, and histological grading ranging from grade 1 to grade 4 is applied to some. Most children with circumscribed astrocytic gliomas, pediatric-type diffuse low-grade gliomas, and glioneuronal and neuronal tumors have a relatively favorable prognosis, especially when a complete surgical resection can be accomplished. Children with pediatric-type diffuse high-grade gliomas generally have a poor prognosis. For information about ependymal tumors, see Childhood Ependymoma Treatment.
The PDQ childhood brain tumor treatment summaries are organized primarily according to the 2021 WHO CNS classification.[1,2]
Childhood gliomas can occur anywhere in the CNS (see Figure 1). For the most common CNS location for each tumor type, see Table 2.
Presenting symptoms for childhood gliomas depend on the following:
Infants and young children with circumscribed gliomas (most commonly pilocytic astrocytomas) and, less frequently, diffuse astrocytomas, involving the hypothalamus may present with diencephalic syndrome, which is manifested by failure to thrive in an emaciated, seemingly euphoric child. Such children may have little in the way of other neurological findings, but may present with macrocephaly, intermittent lethargy, and/or visual impairment.[3]
Children with diffuse midline gliomas centered in the pons (previously called diffuse intrinsic pontine gliomas [DIPGs]) may present with the following classic triad of symptoms; however, children may present with only one or two of these symptoms at diagnosis:
Obstructive hydrocephalus caused by expansion of the pons can also be a presenting symptom. Nonspecific symptoms may also occur, including behavioral changes and decreased school performance.
The presentation of circumscribed astrocytomas (e.g., pilocytic astrocytomas) in the brain stem depends on the tumor location. Common presenting symptoms include the following:[4]
The initial diagnostic evaluation of patients with gliomas includes magnetic resonance imaging (MRI) with and without contrast of the brain and/or spine. The risk of neuraxis dissemination is tumor type dependent, and complete neuraxis imaging, including MRIs of the brain and total spine, may be performed in select patients. In most cases, the specific diagnosis is determined after surgical intervention and pathological classification.
Primary tumors of the brain stem are most often diagnosed on the basis of clinical findings and on neuroimaging studies using MRI, as follows:[5]
Lumbar punctures examining the cerebrospinal fluid for circulating tumor cells are not commonly performed in children with these tumor types.
The pathological classification of pediatric brain tumors is a highly specialized area that continues to evolve. Rapid advances in molecular genetics have led to major improvements in the accurate diagnosis of brain tumors over the past decade. At the same time, many novel brain tumor entities have been recognized on the basis of unique molecular features. Examination of the diagnostic tissue by an experienced neuropathologist is strongly recommended, along with molecular testing, if available.
According to the 2021 WHO CNS classification, gliomas and glioneuronal/neuronal tumors occurring predominantly in childhood are broadly classified as follows:
Within each tumor type, various subtypes are recognized on the basis of histological and molecular features.
The 2021 WHO CNS classification recommends a layered report structure as follows:[1,2]
Whereas CNS tumors were previously graded on histopathological grounds and clinical behavior alone (clinicopathological grading), the 2021 WHO CNS grading scheme employs combined histological and molecular grading for many tumor types.[1] Histological grading ranges from 1 to 4, but not all grades are applied to all tumor types, and some tumor types are not graded.
The 2021 WHO CNS classification and grading of the most common types/subtypes of gliomas, glioneuronal tumors, and neuronal tumors (excluding ependymal tumors) occurring in childhood and adolescence are shown in Table 1.
Tumor Type/Subtype | WHO CNS Grades | |
---|---|---|
Pediatric-type diffuse high-grade gliomas: | ||
Diffuse midline glioma, H3 K27-altered | 4 | |
Diffuse pediatric-type high-grade glioma, H3-wild type and IDH-wild type | 4 | |
Infant-type hemispheric glioma | Not assigned | |
Pediatric-type diffuse low-grade gliomas: | ||
Diffuse low-grade glioma, MAPK pathway-altered | Not assigned | |
Diffuse astrocytoma, MYB- or MYBL1-altered | 1 | |
Circumscribed astrocytic gliomas: | ||
Pilocytic astrocytoma | 1 | |
High-grade astrocytoma with piloid features | Not assigned | |
Pleomorphic xanthoastrocytoma | 2, 3 | |
Subependymal giant cell astrocytoma | 1 | |
Glioneuronal and neuronal tumors: | ||
Ganglioglioma | 1 | |
Desmoplastic infantile ganglioglioma/desmoplastic infantile astrocytoma | 1 | |
Dysembryoplastic neuroepithelial tumor | 1 |
Childhood gliomas can occur anywhere in the CNS, although each tumor type tends to occur in specific anatomical locations (see Table 2).
Tumor Type | Common CNS Location |
---|---|
Circumscribed astrocytic gliomas | Cerebellum, optic nerve, optic chiasm/hypothalamus, thalamus and basal ganglia, brain stem, cerebral hemispheres, and spinal cord (rare) |
Ganglioglioma | Cerebrum, brain stem; occasionally other locations |
Diffuse midline glioma, H3 K27-altered | Pons, thalamus, spinal cord, and other midline structures |
Diffuse pediatric-type high-grade glioma, H3-wild type and IDH-wild type | Cerebrum; occasionally other locations |
Cerebellum: More than 80% of gliomas located in the cerebellum are pilocytic astrocytomas (WHO grade 1) and often cystic; most of the remainder represent pediatric-type diffuse low-grade gliomas.[12] High-grade gliomas in the cerebellum are rare.
Brain stem: The term brain stem glioma is a generic description that refers to any tumor of glial origin arising in the brain stem, inclusive of the midbrain, pons, and medulla. While other histologies (e.g., ganglioglioma) can occur in the brain stem, the following two histologies predominate:
Tumors with exophytic components are overwhelmingly pilocytic astrocytomas.[14] DIPG accounts for approximately 75% to 80% of pediatric brain stem tumors.[15] Most children with DIPGs are diagnosed between the ages of 5 and 10 years. Focal pilocytic astrocytomas in the brain stem occur less frequently.[4]
Optic pathway and hypothalamus: Most tumors arising within the optic pathway (i.e., optic nerve, chiasm, and optic radiations) represent pilocytic astrocytomas, and rarely pediatric-type diffuse low-grade gliomas.[12]
Cerebrum: Most tumors arising in the cerebral hemispheres comprise circumscribed astrocytic gliomas and pediatric-type diffuse low-grade gliomas, followed by pediatric-type diffuse high-grade gliomas.[12]
Children with NF1 have an increased propensity to develop low-grade gliomas, especially in the optic pathway. Up to 20% of patients with NF1 will develop an optic pathway glioma. Most children with NF1-associated optic nerve gliomas are asymptomatic and/or have nonprogressive symptoms and do not require antitumor treatment. Screening magnetic resonance imaging (MRI) in asymptomatic patients with NF1 is usually not indicated, although some investigators perform baseline MRI for young children who cannot undergo detailed ophthalmologic examinations.[16]
The diagnosis is often based on compatible clinical findings and imaging features. Histological confirmation is rarely needed at the time of diagnosis. When biopsies are performed, these tumors are predominantly pilocytic astrocytomas.[12]
Indications for treatment vary, and are often based on the goal of preserving vision.
Very rarely, patients with NF1 develop high-grade gliomas. Sometimes, this tumor is the result of a transformation of a lower-grade tumor.[17]
Patients with tuberous sclerosis have a predilection for developing subependymal giant cell astrocytoma (SEGA). Variants in either TSC1 or TSC2 cause constitutive activation of the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway, leading to increases in proliferation. SEGAs are responsive to molecularly targeted approaches with mTORC1 pathway inhibitors.[18][Level of evidence C2] Patients with tuberous sclerosis are also at risk of developing cortical tubers and subependymal nodules.
Recurrent genomic alterations resulting in constitutive activation of the mitogen-activated protein kinase (MAPK) pathway, most commonly involving the BRAF gene, represent the primary (and often sole) oncogenic driver in the vast majority of pediatric low-grade gliomas, including pilocytic/pilomyxoid astrocytomas, gangliogliomas, and others.[12] As a result, most of these tumors are amenable to molecular targeted therapies.
More complex tumor genomes are characteristic of pediatric diffuse high-grade gliomas. These complex genomes include recurrent genomic alterations in the H3 histone encoding genes (e.g., H3F3A, HIST1H3B), DNA damage repair pathways (e.g., TP53, PPM1D, ATM, MDM2), chromatin modifiers (e.g., ATRX, BCOR, SETD2), cell cycle pathways (e.g., CDKN2A, CDKN2B, RB1), and/or oncogene amplifications (PDGFR, VEGFR2, KIT, MYC, MYCN).[19] For most of these tumors, existing conventional and molecular targeted therapies have limited efficacy.
A rare subset of pediatric high-grade gliomas arising in patients with inheritable biallelic mismatch repair deficiency (bMMRD) is characterized by an extraordinarily high mutational burden. Correctly identifying these patients at the time of diagnosis is critical because of intrinsic resistance to temozolomide and responsiveness to treatment with immune checkpoint inhibitors.[20][Level of evidence C3]; [21]
BRAF activation in pilocytic astrocytoma occurs most commonly through a BRAF::KIAA1549 gene fusion, resulting in a fusion protein that lacks the BRAF autoregulatory domain.[22] This fusion is seen in most infratentorial and midline pilocytic astrocytomas, but is present at lower frequency in supratentorial (hemispheric) tumors.[12]
Presence of the BRAF::KIAA1549 fusion is associated with improved clinical outcome (progression-free survival [PFS] and overall survival [OS]) in patients with pilocytic astrocytoma.[23]; [24][Level of evidence C1] Progression to high-grade gliomas is very rare for pediatric gliomas with the BRAF::KIAA1549 fusion.[24]
Activating point variants in BRAF, most commonly BRAF V600E, are present in a subset of pediatric gliomas and glioneuronal tumors across a wide spectrum of histologies, including pleomorphic xanthoastrocytoma, pilocytic astrocytoma, ganglioglioma, desmoplastic infantile ganglioglioma/astrocytoma, and others.[12] Some low-grade, infiltrative, pediatric gliomas with an alteration in a MAPK pathway gene, including BRAF, and often resembling diffuse low-grade astrocytoma or oligodendroglioma histologically, are now classified as diffuse low-grade glioma, MAPK pathway altered.[1,25]
Retrospective clinical studies have shown the following:
Somatic alterations in NF1 are seen most frequently in children with NF1 and are associated with germline alterations in the tumor suppressor NF1. Loss of heterozygosity for NF1 represents the most common somatic alteration in these patients followed by inactivating variants in the second NF1 allele, and consistent with a second hit required for tumorigenesis. While most NF1 patients with low-grade gliomas have an excellent long-term prognosis, secondary transformation into high-grade glioma may occur in a small subset. Genomically, transformation is associated with the acquisition of additional oncogenic drivers, such as loss of function alterations in CDKN2A, CDKN2B and/or ATRX. Primary high-grade gliomas may also occur in patients with NF1 but are exceedingly rare. Genomic alterations involving the MAPK signaling pathway other than NF1 are very uncommon in gliomas occurring in children with NF1.[17]
High-grade gliomas with distinctive molecular characteristics arise in infants, typically in those diagnosed during the first year of life.[28-30] These tumors are characterized by recurrent oncogenic gene fusions involving ALK, NTRK1, NTRK2, NTRK3, or ROS1 as the primary and, typically, sole oncogenic driver. Infants with this type of glioma, now classified as infant-type hemispheric glioma, have a much better prognosis compared with older children with high-grade gliomas. Remarkably, these tumors may evolve from high-grade to low-grade histology over time, and it remains unclear how much this phenomenon is a consequence of natural disease history versus treatment-induced changes.[28]
ROS1 gene fusions have also been reported in gliomas occurring in older children and adults. A retrospective meta-analysis that included 40 children older than 1 year revealed that ROS1 gene fusions occurred in diverse glioma histologies, including diffuse high-grade and low-grade gliomas and glioneuronal tumors.[30] Similar to ROS1-altered cases occurring in infants, tumor variants in other known driver genes were rare. However, tumor copy number alterations were more frequent in older children than infants.
As an alternative to BRAF activation or NF1 loss, other primary oncogenic driver alterations along the MAPK signaling pathway have been observed in pilocytic astrocytomas and other pediatric-type gliomas. These include oncogenic variants and/or fusions involving FGFR1, FGFR2, PTPN11, RAF1, NTRK2, and others.[12,31,32]
Low-grade gliomas with rearrangements in the MYB family of transcription factors [12,33,34] have now been classified as a separate entity: diffuse astrocytoma, MYB- or MYBL1-altered, WHO grade 1.[1]
Angiocentric gliomas typically arise in children and young adults as cerebral tumors presenting with seizures.[35]
Two reports in 2016 identified MYB gene alterations as being present in almost all cases diagnosed as angiocentric glioma, with QKI being the primary fusion partner in cases where fusion-partner testing was possible.[32,36] While angiocentric gliomas most commonly occur supratentorially, brain stem angiocentric gliomas with MYB::QKI fusions have also been reported.[37,38]
Astroblastomas are defined histologically as glial neoplasms composed of GFAP-positive cells and contain astroblastic pseudorosettes that often demonstrate sclerosis. Astroblastomas are diagnosed primarily in childhood through young adulthood.[35]
The following studies have described genomic alterations associated with astroblastoma:
These reports suggest that the histological diagnosis of astroblastoma encompasses a heterogeneous group of genomically defined entities. Astroblastomas with MN1 fusions represent a distinctive subset of histologically diagnosed cases.[43]
IDH1- and IDH2-altered tumors occur in the pediatric population as low-grade gliomas (WHO Grade 2), high-grade gliomas (WHO Grade 3 and 4), and oligodendrogliomas with codeletion of 1p and 19q. For more information about IDH1- and IDH2-altered gliomas, see the IDH1 and IDH2 variants section in the Molecular features of pediatric-type high-grade gliomas section.
Pediatric high-grade gliomas are biologically distinct from those arising in adults.[44-47]
Pediatric-type high-grade gliomas can be separated into distinct subgroups on the basis of epigenetic patterns (DNA methylation). These subgroups show distinguishing chromosome copy number gains/losses and gene variants in the tumor.[19,48,49] Particularly distinctive subtypes of pediatric high-grade gliomas are those with recurring variants at specific amino acids in histone genes, and together these account for approximately one-half of pediatric high-grade gliomas.[19]
The following pediatric-type high-grade glioma subgroups were identified on the basis of their DNA methylation patterns, and they show distinctive molecular and clinical characteristics:[19]
The histone K27–altered cases occur predominantly in middle childhood (median age, approximately 10 years), are almost exclusively midline (thalamus, brain stem, and spinal cord), and carry a very poor prognosis. The 2021 WHO classification groups these cancers into a single entity: diffuse midline glioma, H3 K27-altered. However, there are clinical and biological distinctions between cases with H3.3 and H3.1 variants, as described below.[1]
Diffuse midline glioma, H3 K27-altered, is defined by loss of H3 K27 trimethylation either due to an H3 K27M variant or, less commonly, overexpression of EZHIP. This entity includes most high-grade gliomas located in the thalamus, pons (diffuse intrinsic pontine gliomas [DIPGs]), and spinal cord, predominantly in children, but also in adults.[50]
H3.3 K27M: H3.3 K27M cases occur throughout the midline and pons, account for approximately 60% of cases in these locations, and commonly present between the ages of 5 and 10 years.[19] The prognosis for H3.3 K27M patients is especially poor, with a median survival of less than 1 year; the 2-year survival rate is less than 5%.[19] Leptomeningeal dissemination is frequently observed in H3.3 K27M patients.[51]
H3.1 K27M: H3.1 K27M cases are approximately fivefold less common than H3.3 K27M cases. They occur primarily in the pons and present at a younger age than other H3.3 K27M patients (median age, 5 years vs. 6–10 years). These patients have a slightly more favorable prognosis than do H3.3 K27M patients (median survival, 15 months vs. 11 months). Variants in ACVR1, which is also the variant observed in the genetic condition fibrodysplasia ossificans progressiva, are present in a high proportion of H3.1 K27M cases.[19,52,53]
H3.2 K27M: Rarely, K27M variants are also identified in H3.2 (HIST2H3C) cases.[19]
A subset of tumors with H3 K27 variants will have a BRAF V600E or FGFR1 co-variant. A retrospective cohort of 29 tumors combined with 31 cases previously reported in the literature demonstrated a somewhat higher propensity for a thalamic location. These cases exhibit a unique DNA methylation cluster that is distinct from other diffuse midline glioma subgroups and glioma subtypes with BRAF or FGFR1 alterations. The median survival for these patients exceeded 3 years.[54] A separate retrospective study of pediatric and adult patients with H3 K27-altered gliomas revealed BRAF V600E variants in 5.8% (9 of 156) and FGFR1 variants in 10.9% (17 of 156) of patients younger than 20 years.[55] Other recurrent genetic alterations detected in pediatric patients included variants in TP53, ATRX, PIK3CA, and amplifications of PDGFRA and KIT. FGFR1 variants were noted to be more frequent in patients older than 20 years (31.8%, 47 of 148).
EZHIP overexpression: The small minority of patients with diffuse midline gliomas lacking histone H3 variants often show EZHIP overexpression.[50] EZHIP inhibits PRC2 activity, leading to the same loss of H3 K27 trimethylation that is induced by H3 K27M variants.[56] Overexpression of EZHIP is likewise observed in posterior fossa type A ependymomas, which also shows loss of H3 K27 methylation.[57]
The H3.3 G34 subtype arises from H3.3 glycine 34 to arginine/valine (G34R/V) variants.[48,49] This subtype presents in older children and young adults (median age, 14–18 years) and arises exclusively in the cerebral cortex.[48,49] H3.3 G34 cases commonly have variants in TP53 and ATRX (95% and 84% of cases, respectively, in one large series) and show widespread hypomethylation across the whole genome. In a series of 95 patients with the H3.3 G34 subtype, 44% of patients also had a variant in PDGFRA at the time of diagnosis, and 81% of patients had PDGFRA variants observed at relapse.[58]
Patients with H3F3A variants are at high risk of treatment failure,[59] but the prognosis is not as poor as that of patients with histone 3.1 or 3.3 K27M variants.[49] O-6-methylguanine-DNA methyltransferase (MGMT) methylation is observed in approximately two-thirds of cases, and aside from the IDH1-altered subtype (see below), the H3.3 G34 subtype is the only pediatric high-grade glioma subtype that demonstrates MGMT methylation rates exceeding 20%.[19]
IDH1- and IDH2-altered tumors occur in the pediatric population as low-grade gliomas (WHO grade 2), high-grade gliomas (WHO grades 3 and 4), and oligodendrogliomas with codeletion of 1p and 19q.[60]
IDH1-altered cases represent a small percentage of high-grade gliomas (approximately 5%–10%) seen in pediatrics, and are almost exclusively older adolescents (median age in a pediatric population, 16 years) with hemispheric tumors.[19,60] These tumors are classified under adult-type diffuse glioma, as astrocytoma, IDH-altered in the 2021 WHO CNS classification. IDH1-altered cases often show TP53 variants, MGMT promoter methylation, and a glioma-CpG island methylator phenotype (G-CIMP).[48,49]
Pediatric patients with IDH1 variants have a more favorable prognosis than patients with other types of high-grade gliomas.[19] A retrospective multi-institutional review of pediatric patients with IDH-altered gliomas and available outcome data (n = 76) reported a 5-year PFS rate of 44% (95% CI, 25%–59%) and a 5-year OS rate of 92% (95% CI, 79%–97%).[60] Approximately 25% of the gliomas in the cohort were classified as high grade. There was no difference in 5-year PFS rates observed between tumor grades. However, patients with high-grade tumors had a worse 5-year OS rate of 75% (95% CI, 40%–91%).
Rare, IDH-altered, high-grade gliomas have been reported to occur in children with mismatch repair–deficiency syndromes (Lynch syndrome or constitutional mismatch repair deficiency syndrome).[61] These tumors, termed primary mismatch repair–deficient IDH-altered astrocytomas (PMMRDIAs), could be distinguished from other IDH-altered gliomas by methylation profiling. PMMRDIAs have molecular features that are distinct from most IDH-altered gliomas, including a hypervariant phenotype and frequent activation of receptor tyrosine kinase pathways. Patients with PMMRDIAs have a markedly worse prognosis than patients with other IDH-altered gliomas, with a median survival of 15 months.
Approximately 10% of pediatric high-grade gliomas have DNA methylation patterns that are PXA-like.[49] PXA-like cases commonly have BRAF V600E variants and a relatively favorable outcome (approximately 50% survival at 5 years).[19,59]
This entity was included in the 2016 WHO classification (called pilocytic astrocytoma with anaplasia) to describe tumors with histological features of pilocytic astrocytoma, increased mitotic activity, and additional high-grade features. The current nomenclature was adopted in the 2021 WHO classification. A more recent publication described a cohort of 83 cases with these histological features (referred to as anaplastic astrocytoma with piloid features) that shared a common DNA methylation profile, which is distinct from the methylation profiles of other gliomas. These tumors occurred more often in adults (median age, 41 years), and they harbored frequent deletions of CDKN2A/B, MAPK pathway alterations (most often in the NF1 gene), and variants or deletions of ATRX. They are associated with a clinical course that is intermediate between pilocytic astrocytoma and IDH–wild-type glioblastoma.[62]
Pediatric patients with glioblastoma multiforme high-grade glioma whose tumors lack both histone variants and IDH1 variants represent approximately 40% of pediatric glioblastoma multiforme cases.[19,63] This is a heterogeneous group, with higher rates of gene amplifications than other pediatric high-grade glioma subtypes. The most commonly amplified genes are PDGFRA, EGFR, CCND/CDK, and MYC/MYCN.[48,49] MGMT promoter methylation rates are low in this group.[63] One report divided this group into three subtypes. The subtype characterized by high rates of MYCN amplification showed the poorest prognosis, while the subtype characterized by TERT promoter variants and EGFR amplification showed the most favorable prognosis. The third group was characterized by PDGFRA amplification.[63]
Infants and young children with high-grade gliomas appear to have tumors with distinctive molecular characteristics [28,29] when compared with tumors of older children and adults with high-grade gliomas. An indication of this difference was noted with the application of DNA methylation analysis to pediatric high-grade tumors, which found that approximately 7% of pediatric patients with a histological diagnosis of high-grade glioma had tumors with methylation patterns more closely resembling those of low-grade gliomas.[19] Ten of 16 infants (younger than 1 year) with a high-grade glioma diagnosis were in this methylation array–defined group.[19] The 5-year survival rate for patients in this report diagnosed at younger than 1 year exceeded 60%, while the 5-year survival rate for patients aged 1 to 3 years and older was less than 20%.
Two studies of the molecular characteristics of high-grade gliomas in infants and young children have further defined the distinctive nature of tumors arising in children younger than 1 year. A key finding from both studies is the importance of gene fusions involving tyrosine kinases (e.g., ALK, NTRK1, NTRK2, NTRK3, and ROS1) in patients in this age group. Both studies also found that infants with high-grade gliomas whose tumors have these gene fusions have survival rates much higher than those of older children with high-grade gliomas.[28,29]
The first study presented data for 118 children younger than 1 year with a low-grade or high-grade glioma diagnosis who had tumor tissue available for genomic characterization.[28] Approximately 75% of the cases were classified as low grade, but the diminished utility of histological classification in this age group was illustrated by the relatively low OS rate for the low-grade cohort (71%) and the relatively favorable survival for the high-grade cohort (55%). Rates of surgical resection were higher for patients with high-grade tumors, a result of many of the low-grade tumors occurring in midline locations while the high-grade tumors were found in supratentorial locations. This finding may also help to explain the relative outcomes for the two groups. Genomic characterization divided the infant glioma population into the following three groups, the first of which included patients with high-grade gliomas:
The second study focused on tumors from children younger than 4 years with a pathological diagnosis of WHO grades 2, 3, and 4 gliomas, astrocytomas, or glioneuronal tumors. Among the 191 tumors studied that met inclusion criteria, 61 had methylation profiles consistent with glioma subtypes that occur in older children (e.g., IDH1, diffuse midline glioma H3 K27-altered, SEGA, pleomorphic xanthoastrocytoma, etc.). The remaining 130 cases were called the intrinsic set and were the focus of additional molecular characterization:[29]
Childhood secondary high-grade glioma (high-grade glioma that is preceded by a low-grade glioma) is uncommon (2.9% in a study of 886 patients). No pediatric low-grade gliomas with the BRAF::KIAA1549 fusion transformed to a high-grade glioma, whereas low-grade gliomas with the BRAF V600E variants were associated with increased risk of transformation. Seven of 18 patients (approximately 40%) with secondary high-grade glioma had BRAF V600E variants, with CDKN2A alterations present in 8 of 14 cases (57%).[24]
Glioneuronal and neuronal tumors are generally low-grade tumors. Select histologies recognized by the 2021 WHO classification include the following:[1]
Ganglioglioma presents during childhood and into adulthood. It most commonly arises in the cerebral cortex and is associated with seizures, but it also presents in other sites, including the spinal cord.[64,65]
The unifying theme for the molecular pathogenesis of ganglioglioma is genomic alterations leading to MAPK pathway activation.[32,66] BRAF alterations are observed in approximately 50% of ganglioglioma cases, with V600E being by far the most common alteration. However, other BRAF variants and gene fusions are also observed. Other less commonly altered genes in ganglioglioma include KRAS, FGFR1, FGFR2, RAF1, NTRK2, and NF1.[32,66]
DIA and DIG most often present in the first year of life and show a characteristic imaging appearance in which a contrast-enhancing solid nodule accompanies a large cystic component.[67,68] DIG is more common than DIA,[67] and by methylation array analysis, both diagnoses cluster together.[69] Survival outcome is generally favorable with surgical resection.[67]
The most commonly observed genomic alterations in DIA and DIG are BRAF variants involving V600. Gene fusions involving kinase genes are observed less frequently.
DNET presents in children and adults, with the median age at diagnosis in mid-to-late adolescence. It is characterized histopathologically by the presence of columns of oligodendroglial-like cells and cortical ganglion cells floating in mucin.[72] The temporal lobe is the most common location, and it is associated with drug-refractory epilepsy.[65,73]
FGFR1 alterations have been reported in 60% to 80% of DNETs, and include FGFR1 activating point variants, internal tandem duplication of the kinase domain, and activating gene fusions.[32,74,75] BRAF variants are uncommon in DNET.
Papillary glioneuronal tumor is a low-grade biphasic neoplasm with astrocytic and neuronal differentiation that primarily arises in the supratentorial compartment.[35] The median age at presentation is in the early 20s, but it can be observed during childhood through adulthood.
The primary genomic alteration associated with papillary glioneuronal tumor is a gene fusion, SLC44A1::PRKCA, that is associated with the t(9:17)(q31;q24) translocation.[76,77] In one study of 28 cases diagnosed histologically as papillary glioneuronal tumor using methylation arrays, 11 of the cases clustered in a distinctive methylation class, while the remaining cases showed methylation profiles typical for other tumor entities. Molecular analysis of the cases in the distinctive methylation cluster showed that all of them had the SLC44A1::PRKCA gene fusion except for a single case with a NOTCH1::PRKCA gene fusion.[78] This suggests that molecular methods for identifying the presence of a PRKCA fusion are less susceptible to misclassification in diagnosing papillary glioneuronal tumor than are morphology-based methods.
RGNT presents in adolescents and adults, with tumors generally located infratentorially, although tumors can arise in mesencephalic or diencephalic regions.[79] The typical histological appearance shows both a glial component and a neurocytic component arranged in rosettes or perivascular pseudorosettes.[35] Outcome for patients with RGNT is generally favorable, consistent with the WHO grade 1 designation.[79]
DNA methylation profiling shows that RGNT has a distinct epigenetic profile that distinguishes it from other low-grade glial/glioneuronal tumor entities.[79] A study of 30 cases of RGNT observed FGFR1 hotspot variants in all analyzed tumors.[79] In addition, PIK3CA activating variants were concurrently observed in 19 of 30 cases (63%). Missense or damaging variants in NF1 were identified in 10 of 30 cases (33%), with 7 tumors having variants in FGFR1, PIK3CA, and NF1. The co-occurrence of variants that activate both the MAPK pathway and the PI3K pathway makes the variant profile of RGNT distinctive among astrocytic and glioneuronal tumors.
DLGNT is a rare CNS tumor that has been characterized radiographically by leptomeningeal enhancement on MRI that may involve the posterior fossa, brain stem region, and spinal cord.[80] Intraparenchymal lesions, when present, typically involve the spinal cord.[80] Localized intramedullary glioneuronal tumors without leptomeningeal dissemination and with histomorphological, immunophenotypic, and genomic characteristics similar to DLGNT have been reported.[81]
DLGNT showed a distinctive epigenetic profile on DNA methylation arrays, and unsupervised clustering of array data applied to 30 cases defined two subclasses of DLGNT: methylation class (MC)-1 (n = 17) and MC-2 (n = 13).[80] Of note, many of the array-defined cases had originally been diagnosed as other entities (e.g., primitive neuroectodermal tumors, pilocytic astrocytoma, and anaplastic astrocytoma). Patients with DLGNT-MC-1 were diagnosed at an earlier age than were patients with DLGNT-MC-2 (5 years vs. 14 years, respectively). The 5-year OS rate was higher for patients with DLGNT-MC-1 than for those with DLGNT-MC-2 (100% vs. 43%, respectively). Genomic findings from the 30 cases of methylation array–defined DLGNT are provided below:
Extraventricular neurocytoma is histologically similar to central neurocytoma, consisting of small uniform cells that demonstrate neuronal differentiation. However, extraventricular neurocytoma arises in the brain parenchyma rather than in association with the ventricular system.[35] It presents during childhood through adulthood.
In a study of 40 tumors histologically classified as extraventricular neurocytoma and subjected to methylation array analysis, only 26 formed a separate cluster distinctive from reference tumors of other histologies.[83] Among cases with an extraventricular neurocytoma methylation array classification for which genomic characterization could be performed, 11 of 15 (73%) showed rearrangements affecting members of the FGFR family, with FGFR1::TACC1 being the most common alteration.[83]
These tumors generally carry a relatively favorable prognosis, particularly for well-circumscribed lesions where a radical resection may be possible.[84,85] With the exception of diffuse leptomeningeal glioneuronal tumors, disseminated or multifocal disease is rare.[86]
Unfavorable clinical prognostic features include the following:[87-89]
On a molecular level, presence of a BRAF V600E variant, especially in conjunction with a CDKN2A or CDKN2B homozygous deletion, has been recognized as a negative prognostic factor, with risk of transformation to a higher-grade tumor. Conversely, the presence of a BRAF::KIAA1549 fusion confers a better clinical outcome in patients with circumscribed astrocytic gliomas.[26][Level of evidence C2]
In children with tumors of the visual pathway, both visual outcomes and clinical assessments are important. Children with isolated optic nerve tumors have a better prognosis than do children with lesions that involve the chiasm or that extend along the optic pathway.[90,91]; [92][Level of evidence C1] Children with NF1 also have a better prognosis, especially when the tumor is found in asymptomatic patients.[93] Better visual acuity at diagnosis, older age at diagnosis, and presence of NF1 are associated with better visual outcomes.[94]
These tumors carry a very poor prognosis with currently available therapies.
Patients with diffuse midline glioma, H3 K27-altered have the poorest prognosis, with 3-year survival rates below 5%.[49]
The following definitions of brain stem tumors are used:
The median survival for children with DIPGs is less than 1 year, although about 10% of children will survive longer than 2 years.[95,96] In contrast, patients with focal astrocytomas (e.g., pilocytic astrocytomas) have a markedly improved prognosis, with 5-year OS rates exceeding 90%.[4]
One report from a clinical trial included 42 children and adolescents with newly diagnosed midline thalamic high-grade gliomas. The study found that tumor location, enhancement pattern, diffusion restriction, and variant status did not significantly affect survival.[97] Leptomeningeal metastatic dissemination and lower surgical resection rates were associated with poorer outcomes.
Prognostic factors include the following:
DIPGs are diffuse astrocytomas that, when biopsied at diagnosis, can range from diffuse astrocytomas (WHO grade 2) to glioblastomas (WHO grade 4). At postmortem evaluation, DIPGs are also generally anaplastic astrocytomas (WHO grade 3) or glioblastomas (WHO grade 4) by morphological criteria, although WHO grade 2 regions can also be identified.[52,53,99-101]
Approximately 80% of DIPGs, regardless of histological grade, demonstrate a histone H3.3 or H3.1 variant and are now classified by the WHO as diffuse midline gliomas, H3 K27M-altered. All diffuse midline gliomas, H3 K27M-altered, are WHO grade 4, regardless of histological grade, reflecting the poor prognosis of children with this diagnosis.
There is no recognized staging system for childhood astrocytomas, other gliomas, and glioneuronal/neuronal tumors. Unifocal disease represents by far the most common initial clinical presentation, followed by multifocal and/or diffuse disease, including leptomeningeal disease. Disease spread outside the central nervous system (CNS) is exceedingly rare.
Spread of diffuse midline glioma in the pons, noted clinically, is usually contiguous, with metastasis via the subarachnoid space. Such dissemination may occur before local progression but usually occurs simultaneously with or after primary disease progression.[1] However, subclinically, more widespread dissemination with extension to the brain stem, thalamus, cerebrum, and supratentorial leptomeninges has been noted at autopsy.[2]
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] Many of the improvements in survival in childhood cancer have been made as a result of clinical trials that have attempted to improve on the best available, accepted therapy. Clinical trials in pediatrics are designed to compare new therapy with therapy that is currently accepted as standard. This comparison may be done in a randomized study of two treatment arms or by evaluating a single new treatment and comparing the results with previously obtained results that assessed an existing therapy. Because of the relative rarity of cancer in children, all patients with brain tumors should be considered for entry into a clinical trial. Information about ongoing National Cancer Institute (NCI)–supported clinical trials is available from the NCI website.
To determine and implement optimal treatment, planning by a multidisciplinary team of cancer specialists who have experience treating childhood brain tumors is required. Irradiation of pediatric brain tumors is technically very demanding and should be carried out in centers that have experience in that area to ensure optimal results.
Long-term management of patients with brain tumors is complex and requires a multidisciplinary approach. 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.
Table 3 describes the standard treatment options for childhood astrocytomas, other gliomas, and glioneuronal/neuronal tumors.
Treatment Group | Standard Treatment Options | |
---|---|---|
Circumscribed astrocytic gliomas, pediatric-type diffuse low-grade gliomas, and glioneuronal/neuronal tumors: | ||
Newly diagnosed | Observation without intervention | |
Surgery | ||
Adjuvant therapy: | ||
—Observation after surgery (no adjuvant therapy) | ||
—Chemotherapy | ||
—Radiation therapy | ||
—Targeted therapy | ||
Progressive/recurrent | Second surgery | |
Radiation therapy | ||
Chemotherapy | ||
Targeted therapy | ||
Pediatric-type diffuse high-grade gliomas: | ||
Newly diagnosed | Surgery | |
Adjuvant therapy: | ||
—Radiation therapy | ||
—Chemotherapy | ||
Targeted therapy | ||
Immunotherapy | ||
Recurrent | Second surgery (not considered standard treatment) | |
Radiation therapy (not considered standard treatment) | ||
Targeted therapy (not considered standard treatment) | ||
Immunotherapy (not considered standard treatment) |
To determine and implement optimal management, treatment is best guided by a multidisciplinary team of specialists experienced in treating pediatric patients with brain tumors.
For children with optic pathway gliomas, an important primary goal of treatment is preservation of visual function.[1]
Standard treatment options for newly diagnosed circumscribed astrocytic gliomas, pediatric-type diffuse low-grade gliomas, and glioneuronal/neuronal tumors include the following:
Observation, without any intervention, is an option for patients with neurofibromatosis type 1 (NF1) or incidentally found, asymptomatic tumors.[2] Spontaneous regressions of optic pathway gliomas have been reported in children with and without NF1.[3,4]
Surgical resection is a primary treatment,[5,6] and surgical feasibility depends on tumor location. For example, safe surgical resection may not be feasible in many patients with optic pathway gliomas, because even a biopsy may present risks to the patient's vision. As a result, a diagnosis of an optic pathway glioma may rely on a compatible history and imaging findings alone. This is especially true in patients with NF1.[5] For other clinical presentations of an optic pathway tumor, particularly when the tumor is more infiltrative, a biopsy may be considered for molecular characterization of the tumor.
For patients presenting with obstructive hydrocephalus, a shunt or other cerebrospinal fluid diversion procedure may also be needed.
In general, for focal brain stem gliomas, particularly those arising in the pons and medulla, maximal safe surgical resection is attempted.[9] While a greater extent of resection is associated with a higher progression-free survival (PFS), this must be balanced with the risk of new postsurgical complications. In a series of 116 patients with low-grade gliomas of the brain stem, 100 patients had some surgical intervention. Twenty-seven patients underwent a biopsy, only one of whom had new postoperative deficits. Seventy-three patients underwent a complete or partial resection, and almost 30% of this group had significant postoperative complications, including respiratory insufficiency (five patients), cerebellar mutism (three patients), and cranial nerve palsies or paresis (15 patients).[10]
After resection, immediate (within 48 hours of resection per Children’s Oncology Group [COG] criteria) postoperative magnetic resonance imaging is obtained. Surveillance scans are then obtained periodically for completely resected tumors, although the value following the initial 3- to 6-month postoperative period is uncertain.[12]; [13][Level of evidence C2]
Factors related to outcome for children with low-grade gliomas treated with surgery followed by observation were identified in a COG study that included 518 evaluable patients.[6] Overall outcome for the entire group was an 8-year PFS rate of 78% and an 8-year overall survival (OS) rate of 96%. The following factors were related to prognosis:[6]
A multivariate analysis examined 100 patients with confirmed diagnoses of World Health Organization (WHO) grade 2 diffuse gliomas treated in an International Society of Paediatric Oncology (SIOP) study. The extent of glioma resection had the greatest impact on event-free survival (EFS) rates. The 5-year EFS rates were 75% to 76% for patients who underwent a complete or subtotal resection. In comparison, 5-year EFS rates were 56% for patients who had a partial resection and 19% for patients who had a biopsy.[14][Level of evidence B4]
The extent of resection necessary for cure is unknown because patients with microscopic and even gross residual tumor after surgery may experience long-term PFS without postoperative therapy.[5,6]
The long-term functional outcome of patients with cerebellar pilocytic astrocytomas is relatively favorable. Full-scale mean intelligence quotients (IQs) of patients with low-grade gliomas treated with surgery alone are close to the normative population. However, these patients may have long-term medical, psychological, and educational deficits.[16]; [17,18][Level of evidence C1]
Adjuvant therapy following complete resection is generally not required unless there is a subsequent recurrence of disease. Treatment options for patients with incompletely resected tumor must be individualized and may include one or more of the following:
Patients whose tumors have been partially resected may be observed without further disease-directed treatment, particularly if the pace of tumor regrowth is anticipated to be very slow. Approximately 50% of patients with less-than-gross total resections have disease that does not progress in 5 to 8 years, supporting the observation strategy in selected patients.[6]
Given the long-term side effects associated with radiation therapy, chemotherapy is recommended as first-line therapy for most pediatric patients who require adjuvant therapy after surgery.
Chemotherapy may result in objective tumor shrinkage and help avoid, or at least delay, the need for radiation therapy in most patients.[19-21] Chemotherapy is also an option for adolescents with optic nerve pathway gliomas to delay or avoid radiation therapy.[22][Level of evidence C2] Chemotherapy has been shown to shrink tumors in children with hypothalamic gliomas and the diencephalic syndrome, resulting in weight gain in those who respond to treatment.[23]
The most widely used regimens to treat tumor progression or symptomatic nonresectable, pediatric low-grade gliomas are the following:
The COG reported the results of a randomized phase III trial (COG-A9952) that treated children younger than 10 years with low-grade chiasmatic/hypothalamic gliomas without NF1 using one of two regimens: carboplatin and vincristine (CV) or TPCV. The 5-year EFS rate was 39% (± 4%) for patients who received the CV regimen and 52% (± 5%) for patients who received the TPCV regimen. Toxicity rates between the two regimens were relatively comparable.[19] In the same study, children with NF1 were nonrandomly assigned to receive treatment with CV. The 5-year EFS rate for children with NF1 was markedly better, at 69% (± 4%), than it was for children without NF1 who received CV. In multivariate analysis, NF1 was an independent predictor of better EFS but not OS.[30] In a separate study that included 100 patients with WHO grade 2 diffuse gliomas, a subset of patients (n = 16) were treated with CV, and some patients also received etoposide. This subset of patients had a 5-year PFS rate of 38% when patients with histone H3 variants were excluded.[14][Level of evidence B4]
Other chemotherapy approaches that have been employed to treat children with progressive or symptomatic nonresectable, low-grade astrocytomas include the following:
Among children who received chemotherapy for optic pathway gliomas, those without NF1 had higher rates of disease progression than those with NF1, and infants had higher rates of disease progression than children older than 1 year.[20,21,28] Visual status (including acuity and field) is an important measure of outcome and response to treatment. Vision function can be impaired; it is variable even in patients with radiographic responses and is often less than optimal. More than one-third of patients successfully treated with chemotherapy have poor vision in one or both eyes, and some patients lose vision despite radiographic evidence of tumor control (response or stability). In most series, children with sporadic visual pathway gliomas have poorer visual outcomes than do children with NF1.[28]; [37,38][Level of evidence C1] Better initial visual acuity, older age, and absence of postchiasmatic involvement are associated with improved or stable vision after chemotherapy.[39,40]
Radiation therapy is usually reserved for patients with disease that does not durably respond to chemotherapy.[20,21,41,42]
For children with low-grade gliomas for whom radiation therapy is indicated, approaches that contour the radiation distribution to the tumor and avoid normal brain tissue (3-D conformal radiation therapy, intensity-modulated radiation therapy (IMRT), stereotactic radiation therapy, and proton radiation therapy [charged-particle radiation therapy]) can reduce the acute and long-term toxicities associated with these modalities.[43,44]; [45][Level of evidence C2] Radiation doses of 54 Gy in 1.8 Gy fractions are typically used.[46,47] In a prospective study of 174 patients treated with proton therapy, the 5-year actuarial rate of local control was 85% (95% confidence interval [CI], 78%–90%), the PFS rate was 84% (95% CI, 77%–89%), and the OS rate was 92% (95% CI, 85%–95%). Brain stem and spinal cord tumor locations and a dose of 54 Gy relative biological effectiveness (RBE) or less were associated with inferior local control (P < .01 for both).[48] In a separate study that included 100 patients with WHO grade 2 diffuse gliomas, a subset of patients (n = 16) were treated with radiation therapy. These patients had a 5-year PFS rate of 74% when patients with histone H3 variants were excluded.[14][Level of evidence B4]
Subsequent to radiation therapy administration, care must be taken to distinguish radiation-induced imaging changes, termed pseudoprogression or spurious progression,[49] from disease progression. The peak time to radiation therapy–induced imaging changes, often presenting as an apparent enlargement of the irradiated mass, is 4 to 6 months, but they can manifest even later.[50-53]; [54,55][Level of evidence B4]; [8,56,57][Level of evidence C2] In a report of 83 patients with low-grade astrocytomas, pseudoprogression was more common after radiation doses of higher than 50.4 Gy (RBE) (hazard ratio [HR], 2.61; P = .16). Pseudoprogression was also more common after proton radiation therapy than after photon IMRT (HR, 2.15; P = .048), presumably because of increased effects on the vasculature. Patients with pilocytic histology had lower rates of pseudoprogression than those with nonpilocytic low-grade gliomas (HR, 0.47; P = .037). There was no association with overall disease control.[49]
A report from the SIOP-LGG 2004 (NCT00276640) study and LGG-registry cohorts evaluated the following radiological criteria for pseudoprogression:[58]
The following results were observed:
Radiation therapy results in long-term radiographic disease control for most children with chiasmatic and posterior pathway chiasmatic gliomas. However, despite radiological control, visual outcomes are variable.
The management of unresectable circumscribed astrocytic gliomas, pediatric-type diffuse low-grade gliomas, glioneuronal tumors, and neuronal tumors is controversial. To identify negative prognostic features in patients treated with radiation therapy, the St. Jude Children’s Research Hospital assessed 150 children (median age, 8 years; range, 1.2–20 years) who received radiation therapy and were monitored for a median of 11.4 years (range, 0.24–29.4 years). Recursive positioning analysis yielded low-risk and high-risk prognostic groups. The 10-year OS rate was 95.6% for patients in the low-risk group, versus 76.4% for patients in the high-risk group. Low-risk tumors included pilocytic astrocytoma/ganglioglioma located outside of the midbrain/thalamus, while high-risk tumors included diffuse astrocytoma or those located in the midbrain/thalamus. Within the high-risk group of patients, delayed radiation therapy (defined as after at least one line of chemotherapy) was associated with a decrement in OS.[64]
Children with NF1 may be at higher risk of radiation-associated secondary tumors and morbidity resulting from vascular changes. Radiation therapy is used as a last resort in these patients, given the heightened risk of inducing neurological toxic effects and second malignancy.[65]
The U.S. Food and Drug Administration approved the combination of trametinib (MEK inhibitor) plus dabrafenib (BRAF inhibitor) for the treatment of pediatric patients aged 1 year and older with low-grade gliomas and a BRAF V600E variant who require systemic therapy. The approval was based on a randomized clinical trial that compared the dabrafenib-plus-trametinib combination with the carboplatin-plus-vincristine combination. The median age of enrolled patients was 9.5 years, and the most common histological subtypes were ganglioglioma (about 25%) and pilocytic astrocytoma (about 30%). Patients were randomly assigned in a 2-to-1 ratio, with 73 receiving dabrafenib plus trametinib and 37 receiving carboplatin plus vincristine. Patients received dabrafenib and trametinib until loss of clinical benefit or until unacceptable toxicity, and the carboplatin-plus-vincristine combination was given as a 10-week induction course, followed by eight 6-week cycles of therapy.[66]
IDH inhibitors are being studied for the treatment of patients with IDH-altered low-grade and high-grade gliomas. One agent, vorasidenib, has shown preliminary evidence of activity in delaying the time to progression when compared with placebo in newly diagnosed adults with IDH1- or IDH2-altered low-grade gliomas.[67]
For children with tuberous sclerosis (TS) and symptomatic subependymal giant cell astrocytomas (SEGAs), agents that inhibit mammalian target of rapamycin (mTOR) (e.g., everolimus and sirolimus) have been studied.
Evidence (treatment of SEGA with an mTOR inhibitor):
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 are examples of national and/or institutional clinical trials that are currently being conducted:
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.
There is no single standard treatment option for progressive/recurrent circumscribed astrocytic gliomas, pediatric-type diffuse low-grade gliomas, glioneuronal tumors, and neuronal tumors. To determine and implement optimal management, treatment is best guided by a multidisciplinary team of specialists with experience treating pediatric patients with brain tumors.
An individual plan needs to be tailored on the basis of the following:
Recurrent disease is usually at the primary tumor site, although multifocal or widely disseminated disease to other intracranial sites and to the spinal leptomeninges has been documented.[1,2] Most recurrences are of the same tumor entity; however, transformation into a higher grade tumor is possible and associated with the molecular profile.[3] Surveillance imaging will frequently identify asymptomatic recurrences.[4] At the time of recurrence, a complete evaluation to determine the extent of the relapse is indicated.
Tumor sample sequencing was done in pediatric (n = 48) and young adult patients (n = 6) with recurrent or refractory low-grade gliomas who were enrolled in the National Cancer Institute (NCI)–Children's Oncology Group (COG) Pediatric MATCH trial. The test revealed genomic alterations that were considered actionable for treatment on MATCH study arms in 39 of 54 tumors (72.2%).[5] Alterations in MAPK pathway genes (most commonly BRAF and NF1) were detected in 26 of 54 tumors (48.1%). FGFR1 variants (n = 11) or fusions (n = 1) were identified in 12 of 54 tumors (22.2%).
Treatment options for progressive/recurrent circumscribed astrocytic gliomas, pediatric-type diffuse low-grade gliomas, and glioneuronal/neuronal tumors include the following:
Consideration of surgical intervention must be individualized on the basis of the following:
Utility of second surgery is impacted by site of recurrence and the probability of obtaining a near-total resection/gross-total resection without significant neurological injury.[6]
The rationale for the use of radiation therapy is essentially the same for first-line therapy or at the time of recurrence. For more information, see the Radiation therapy section. If the child has never received radiation therapy, local radiation therapy may be a treatment option, although chemotherapy in lieu of radiation should be considered, depending on the child's age and the extent and location of the tumor.[7][Level of evidence C1]; [8][Level of evidence C2]
For children with low-grade gliomas for whom radiation therapy is indicated, conformal radiation therapy (including proton-beam therapy) approaches appear effective and offer the potential for reducing the acute and long-term toxicities associated with this modality.[9-12]
If there is recurrence or progression at an unresectable site, chemotherapy should be considered.
Chemotherapy may result in relatively long-term disease control.[13,14] The choice of regimen depends on the type of and response to prior chemotherapy. Numerous options can be considered, most commonly including carboplatin with or without vincristine (CV); thioguanine, procarbazine, lomustine, and vincristine (TPCV); or vinblastine alone; temozolomide alone; temozolomide in combination with carboplatin and vincristine; irinotecan and bevacizumab; or lenalidomide.[13-17] When a therapeutically actionable molecular alteration is identified in the tumor, molecular targeted therapy is increasingly being used as second-line therapy.
For children with tuberous sclerosis (TS) and symptomatic subependymal giant cell astrocytomas (SEGAs) or low-grade gliomas,[18] mammalian target of rapamycin (mTOR) inhibitors (e.g., everolimus and sirolimus) have been studied.
Evidence (mTOR inhibitors):
Antitumor activity has also been observed for bevacizumab given in combination with irinotecan, which, in some cases, also results in clinical or visual improvement.[27]
Evidence (targeted therapy [bevacizumab]):
With the identification of BRAF variants driving a significant proportion of low-grade gliomas, inhibition of various elements of this molecular pathway (e.g., MEK and BRAF) are actively being tested in ongoing clinical trials, with early reports suggesting substantial activity. While first-generation BRAF inhibitors like vemurafenib and dabrafenib are active against tumors with BRAF V600E variants, they are contraindicated for tumors with BRAF gene fusions because of the potential for paradoxical activation of the MAPK pathway.[34,35] As described below, the U.S. Food and Drug Administration (FDA) approved the dabrafenib-plus-trametinib combination for use in pediatric patients aged 1 year and older with relapsed or refractory low-grade gliomas with BRAF V600E variants.
The most common toxicities across all strata were grade 1 and grade 2 CPK elevation, diarrhea, hypoalbuminemia, elevated aspartate aminotransferase (AST), and rash. Rare grade 3 and grade 4 toxicities included elevated CPK, rash, neutropenia, emesis, and paronychia.
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 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:
Patients with tumors that have molecular variants addressed by open treatment arms in the trial may be enrolled in treatment on Pediatric MATCH. Additional information can be obtained on the NCI website and 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.
To determine and implement optimal management, treatment is best guided by a multidisciplinary team of specialists experienced in treating pediatric patients with brain tumors.
The outcome for pediatric patients with the most common types of high-grade glioma (i.e., diffuse midline glioma, H3 K27-altered and diffuse pediatric-type high-grade glioma, H3-wild type and IDH-wild type) remains dismal.[1] In contrast, the prognosis for children with infant-type hemispheric glioma is relatively favorable.[2,3]
Maximal safe surgical resection can be considered standard of care for all patients with pediatric-type diffuse high-grade glioma.[4]
Standard adjuvant therapy for children with diffuse pediatric-type high-grade glioma, H3-wild type and IDH-wild type, includes radiation therapy and alkylator chemotherapy.[5-7]
For children with diffuse midline glioma, H3 K27-altered (the most common subtype), including those with diffuse intrinsic pontine glioma (DIPG), adjuvant radiation therapy alone can be considered standard of care given the apparent lack of benefit of chemotherapy.[8,9]
Standard treatment options for newly diagnosed pediatric-type diffuse high-grade gliomas include the following:
The extent of tumor resection at initial diagnosis is positively associated with survival. Therefore, maximal safe resection is recommended for children with nonpontine tumors.[4,10,11]
For children with diffuse midline glioma in the pons (DIPG), histological confirmation is increasingly obtained for both entry into research studies and molecular characterization of the tumor.[12] New approaches with stereotactic needle biopsy may make biopsy safer.[13-16] Given the technical challenges of pontine biopsies, the procedure is best undertaken by an experienced pediatric neurosurgeon to minimize the risk of irreversible neurological complications.[13-17] Biopsy is recommended for pontine tumors when the diagnosis is uncertain based on imaging findings.
For patients with diffuse midline glioma, H3 K27-altered and diffuse pediatric-type high-grade glioma, H3-wild type and IDH-wild type, focal radiation therapy is routinely administered to a field that widely encompasses the entire tumor. The radiation therapy dose to the tumor bed is usually at least 54 Gy. Despite such therapy, the prognosis is dismal. Similarly poor survival is seen in children with spinal cord primary tumors and children with thalamic high-grade gliomas (i.e., diffuse midline gliomas, H3 K27M-altered tumors) treated with radiation therapy.[18,19]; [20,21][Level of evidence C1]
Standard treatment for children with diffuse midline gliomas centered in the pons is radiation therapy to the involved site. The conventional dose of radiation ranges between 54 Gy and 60 Gy, given locally to the primary tumor site in single daily fractions. Such treatment will result in transient benefit for most patients, but more than 90% of patients will die within 18 months of diagnosis.[22]
Radiation-induced changes may occur a few months after the completion of radiation therapy and may mimic tumor progression. When considering the efficacy of additional treatment, care needs to be taken to separate radiation-induced change from progressive disease.[23]
Research studies that evaluated the efficacy of hyperfractionated and hypofractionated radiation therapy and radiosensitizers have not demonstrated improved outcomes using these radiation techniques.
For patients with diffuse pediatric-type high-grade glioma, H3-wild type and IDH-wild type, the benefit from radiation therapy with adjuvant chemotherapy compared with radiation therapy alone has not been formally proven in a randomized prospective trial. However, the aggregate data from numerous nonrandomized prospective clinical trials for children with high-grade gliomas suggest a benefit from alkylating chemotherapy, similar to adults with primary glioblastoma. Therefore, adjuvant therapy with a combination of radiation therapy and alkylating chemotherapy can be considered standard of care. Commonly used chemotherapy regimens include temozolomide alone or in combination with lomustine.[5,6]
Prospective, randomized clinical trials in adults with primary glioblastoma have established MGMT promoter hypermethylation as an independent prognostic biomarker regardless of therapy, as well as a predictive biomarker for benefit from temozolomide.[35,36] However, in children with diffuse pediatric-type high-grade glioma, H3-wild type and IDH-wild type, MGMT promoter methylation status is not prognostic,[8,37] and its predictive value for benefit from alkylator chemotherapy is unknown given the lack of applicable randomized data.
In a prospective randomized trial, the use of adjuvant bevacizumab after radiation therapy did not prolong overall survival (OS) or progression-free survival (PFS) in pediatric patients with newly diagnosed high-grade gliomas.[7]
No chemotherapy (including neoadjuvant, concurrent, postradiation chemotherapy) or immunotherapy strategy, when added to radiation therapy, has led to long-term survival for children with DIPGs.[38-40]; [41][Level of evidence B4] This includes therapy using high-dose, marrow-ablative chemotherapy with autologous hematopoietic stem cell rescue, which has been shown to be ineffective in extending survival.[42] However, similar to the treatment of other brain tumors, radiation therapy is generally omitted for infants with DIPGs, and chemotherapy-only approaches are used. Published data supporting the utility of this approach are lacking.
Children with infant-type hemispheric gliomas have been categorized into three groups.[43] Group 1 tumors include high-grade gliomas that are hemispheric and receptor tyrosine kinase (RTK) driven, including ALK, NTRK, ROS1, and MET gene fusions. Previously, infants with such tumors were treated with adjuvant multiagent chemotherapy instead of radiation therapy, with relatively favorable outcomes.[9,44]
Therapeutically targetable somatic BRAF V600E variants are present in a small subset of patients with pediatric-type diffuse high-grade gliomas. Data from a nonrandomized retrospective study suggest that up-front inclusion of BRAF and/or MEK inhibitor therapy in place of chemotherapy may result in improved survival.[45][Level of evidence C2]
There is evidence that infants with group 1 hemispheric high-grade gliomas that have specific RTK-driven gene fusions are responsive to RTK-targeted therapeutics.[43,46] A subset analysis included 33 patients with NTRK fusion–positive central nervous system tumors who were treated with larotrectinib (included in two larger trials that enrolled children and adults with solid tumors and NTRK fusions).[47] The objective response rate was 30%, and 82% of patients with measurable disease had tumor shrinkage. The 12-month duration of response rate was 75%, the PFS rate was 56%, and the OS rate was 85%.[47] The role of RTK inhibitors in the up-front treatment of infants with pediatric-type high-grade glioma remains under study.
Children with inheritable biallelic mismatch repair deficiency have a very high mutational burden and neoantigen expression. These patients are at risk of developing a variety of cancers, including hematologic malignancies, gastrointestinal cancers, and high-grade gliomas. The high variant and neoantigen load have been associated with responsiveness to immune checkpoint inhibition. Early case reports have demonstrated clinical imaging responses in children who are treated with an anti-programmed death-1 inhibitor.[48]
Therapeutic clinical 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 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:
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.
To determine and implement optimal management, treatment is best guided by a multidisciplinary team of specialists experienced in treating pediatric patients with brain tumors.
Treatment options for recurrent pediatric-type diffuse high-grade gliomas include the following:
The use of surgical intervention must be individualized on the basis of the following:
Radiation therapy is appropriate for patients who have not previously been irradiated. Radiation doses and volumes are similar to those used for newly diagnosed patients. Generally, this is limited to young children initially treated with radiation-avoiding strategies.
For previously irradiated patients with non–brain stem pediatric-type high-grade gliomas, reirradiation has been used, although the data demonstrating benefit are sparse. Stereotactic radiosurgery (SRS) or stereotactic radiation therapy (SRT) techniques using either hypofractionated radiation therapy or standard fraction sizes may be considered. For small volume distinct lesions, SRS allows for maximum sparing of normal tissues. For more infiltrative lesions, fractionated radiation therapy may better spare normal tissues.[1]
For patients with DIPG, reirradiation has been shown to prolong survival and can be considered at progression in children who have had an initial response to radiation therapy.[2,3] In a phase I/II study of 12 patients treated at three dose levels (24 Gy/12 fractions, 26.5 Gy/12 fractions, or 30.8 Gy/14 fractions), almost all patients improved. Clinical utility analysis showed that the 24-Gy regimen was preferable.[4] A recent survey confirms the effective use of even lower doses (e.g., 12 Gy fractionated). These doses are beneficial, and they allow for additional radiation therapy courses.[5]
Somatic BRAF V600E variants are present in a small subset of patients. While many of these tumors are responsive to BRAF and/or MEK inhibitors, responses in the recurrent setting are typically not sustained long term. A median progression-free survival of approximately 3 months was reported in one retrospective series.[6] In a multicenter, open-label, single-arm, phase II trial that evaluated dabrafenib plus trametinib, 15 of 45 adult patients with BRAF V600E variants and high-grade gliomas had an objective response. There were three complete responses and 12 partial responses, with a median overall survival of 17.6 months.[7]
The U.S. Food and Drug Administration (FDA) approved the combination of dabrafenib (BRAF inhibitor) plus trametinib (MEK inhibitor) for adult and pediatric patients aged 1 year and older with unresectable or metastatic solid tumors with BRAF V600E variants who have progressed following prior treatment and have no satisfactory alternative treatment options.[8,9] This approval includes pediatric patients aged 1 year and older with BRAF V600E variants and high-grade gliomas. The approval for this patient population was based on the results described below:[8-10]
Activating gene fusions (ALK, NTRK1, NTRK2, NTRK3, ROS1, and MET) are characteristic of infant-type diffuse gliomas.[11,12] Data from case reports and recent prospective clinical trials suggest that these tumors are highly responsive to targeted therapies.[13]
Tumor sample sequencing was done in pediatric (n = 54) and young adult patients (n = 15) with recurrent or refractory high-grade gliomas who were enrolled in the National Cancer Institute (NCI)–Children's Oncology Group (COG) Pediatric MATCH trial. The test revealed genomic alterations that were considered actionable for treatment on MATCH study arms in 36 of 69 tumors (52.2%).[14] Alterations in MAPK pathway genes were detected in 17 of 69 tumors (24.6%), most frequently BRAF V600E variants or fusions (n = 11, 15.9%). FGFR1 variants or fusions were identified in 6 of 69 tumors (8.7%).
Numerous studies are investigating a variety of immunotherapy strategies, including checkpoint inhibitors, oncolytic viruses, chimeric antigen receptor (CAR) T cells, and other immune-modulating strategies. The utility of such strategies in the treatment of patients with recurrent pediatric-type diffuse high-grade gliomas is under study, with preliminary evidence of activity in some settings.[15,16]
The role of immune checkpoint inhibition in the treatment of children with recurrent high-grade astrocytoma is currently under study. Children with biallelic mismatch repair deficiency have a very high mutational burden and neoantigen expression and are at risk of developing a variety of cancers, including hematologic malignancies, gastrointestinal cancers, and brain tumors. The high variant and neoantigen load has been correlated with improved response to immune checkpoint inhibition. Early case reports have demonstrated clinical and radiographic responses in children who are treated with an anti–programmed death-1 inhibitor.[17]
Patients for whom initial treatment fails may benefit from additional treatment, including entry into clinical trials of novel therapeutic approaches.[18] 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 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:
Patients with tumors that have molecular variants addressed by open treatment arms in the trial may be enrolled in treatment on Pediatric MATCH. Additional information can be obtained on the NCI website and 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.
General Information About Childhood Astrocytomas, Other Gliomas, and Glioneuronal/Neuronal Tumors
Added Das et al. as reference 21.
Added text to state that ROS1 gene fusions have been reported in gliomas occurring in older children and adults. A retrospective meta-analysis that included 40 children older than 1 year revealed that ROS1 gene fusions occurred in diverse glioma histologies, including diffuse high-grade and low-grade gliomas and glioneuronal tumors. Similar to ROS1-altered cases occurring in infants, tumor variants in other known driver genes were rare. However, tumor copy number alterations were more frequent in older children than infants (cited Meredith et al. as reference 30).
Added text to state that a subset of H3 K27-altered tumors will have a BRAF V600E or FGFR1 co-variant. Added text about the results of a retrospective study that demonstrated a somewhat higher propensity for a thalamic location (cited Auffret et al. as reference 54). Also added text about the results of a separate retrospective study of pediatric and adult patients with H3 K27-altered gliomas that revealed BRAF V600E variants in 5.8% and FGFR1 variants in 10.9% of patients younger than 20 years (cited Williams et al. as reference 55).
Added text to state that the small minority of patients with diffuse midline gliomas lacking histone H3 variants often show EZHIP overexpression. EZHIP inhibits PRC2 activity, leading to the same loss of H3 K27 trimethylation that is induced by H3 K27M variants (cited Jain et al. as reference 56). Overexpression of EZHIP is likewise observed in posterior fossa type A ependymomas, which also shows loss of H3 K27 methylation (cited Hübner et al. as reference 57).
Added text about the prevalence, presentation, and genomics of IDH1- and IDH2-altered tumors that occur in the pediatric population.
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 astrocytomas, other gliomas, and glioneuronal/neuronal 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.
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 Astrocytomas, Other Gliomas, and Glioneuronal/Neuronal Tumors 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 Astrocytomas, Other Gliomas, and Glioneuronal/Neuronal Tumors Treatment. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/types/brain/hp/child-astrocytoma-glioma-treatment-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389382]
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.