The PDQ childhood brain tumor treatment summaries are organized primarily according to the World Health Organization classification of nervous system tumors.[1,2] For a full description of the classification of nervous system tumors and a link to the corresponding treatment summary for each type of brain tumor, refer to the PDQ summary on Childhood Brain and Spinal Cord Tumors Treatment Overview.
Dramatic improvements in survival have been achieved for children and adolescents with cancer. Between 1975 and 2002, childhood cancer mortality has decreased by more than 50%. Childhood and adolescent cancer survivors require close follow-up because cancer therapy side effects may persist or develop months or years after treatment. Refer to the PDQ summary on Late Effects of Treatment for Childhood Cancer for specific information about the incidence, type, and monitoring of late effects in childhood and adolescent cancer survivors.
Primary brain tumors are a diverse group of diseases that together constitute the most common solid tumor of childhood. Brain tumors are classified according to histology, but tumor location and extent of spread are important factors that affect treatment and prognosis. Immunohistochemical analysis, cytogenetic and molecular genetic findings, and measures of mitotic activity are increasingly used in tumor diagnosis and classification.Clinicopathologic Classification of Childhood Astrocytomas and Other Tumors of Glial Origin
The pathologic classification of pediatric brain tumors is a specialized area that is undergoing evolution; review of the diagnostic tissue by a neuropathologist who has particular expertise in this area is strongly recommended.
Childhood astrocytomas and other tumors of glial origin are classified according to clinicopathologic and histologic subtype and are histologically graded from grade I to IV according to the World Health Organization’s (WHO) histologic typing of central nervous system (CNS) tumors. Tumor types are based on the glial cell type of origin: astrocytomas (astrocytes), oligodendroglial tumors (oligodendrocytes), mixed gliomas (cell types of origin include oligodendrocytes, astrocytes, and ependymal cells) and neuronal tumors (with or without an astrocytic component).
WHO histologic grades are commonly referred to as low-grade gliomas or high-grade gliomas (see Table 1).Table 1. World Health Organization (WHO) Histologic Grade and Corresponding Classification for Tumors of the Central Nervous System
|WHO Histologic Grade||Grade Classification|
In 2007, the WHO further categorized astrocytomas, oligodendroglial tumors, and mixed gliomas according to histopathologic features and biologic behavior. It was determined that the pilomyxoid variant of pilocytic astrocytoma may be a more aggressive variant and may be more likely to disseminate, and it was reclassified by the WHO as a grade II tumor (see Table 2).[1,2,4]Table 2. Histologic Grade of Childhood Astrocytomas and Other Tumors of Glial Origin
|Type||WHO Histologic Grade|
|Subependymal giant cell astrocytoma||I|
Childhood astrocytomas and other tumors of glial origin can occur anywhere in the CNS, although each tumor type tends to have preferential CNS locations (see Table 3).Table 3. Childhood Astrocytomas and Other Tumors of Glial Origin and Preferential Central Nervous System (CNS) Location
|Tumor Type||Preferential CNS location|
|Pilocytic astrocytoma||Optic nerve, optic chiasm/hypothalamus, thalamus and basal ganglia, cerebral hemispheres, cerebellum, brain stem, and spinal cord (rare)|
|Pleomorphic xanthoastrocytoma||Superficial location in cerebrum (temporal lobe preferentially)|
|Diffuse astrocytoma (including fibrillary)||Cerebrum (frontal and temporal lobes), brain stem, spinal cord, optic nerve, optic chiasm, optic pathway, hypothalamus, and thalamus|
|Anaplastic astrocytoma, glioblastoma||Cerebrum; occasionally cerebellum, brain stem, and spinal cord|
|Oligodendrogliomas||Cerebrum (frontal lobe preferentially followed by temporal, parietal, and occipital lobes), cerebellum, brain stem, and spinal cord|
|Oligoastrocytoma||Cerebral hemispheres (frontal lobe preferentially followed by the temporal lobe)|
|Gliomatosis cerebri||Cerebrum with or without brain stem involvement, cerebellum, and spinal cord|
More than 80% of astrocytomas located in the cerebellum are low-grade (pilocytic grade I) and often cystic; most of the remainder are diffuse grade II astrocytomas. Malignant astrocytomas in the cerebellum are rare.[1,2] The presence of certain histologic features has been used retrospectively to predict event-free survival for pilocytic astrocytomas arising in the cerebellum or other location.[5-7]
Astrocytomas arising in the brain stem may be either high-grade or low-grade, with the frequency of either type being highly dependent on the location of the tumor within the brain stem.[8,9] Tumors not involving the pons are overwhelmingly low-grade gliomas (e.g., tectal gliomas of the midbrain), whereas tumors located exclusively in the pons without exophytic components are largely high-grade gliomas (e.g., diffuse intrinsic pontine gliomas).[8,9]
Children with neurofibromatosis type 1 (NF1) have an increased propensity to develop WHO grade I and II astrocytomas in the visual pathway; approximately 20% of all patients with NF1 will develop a visual pathway glioma. In these patients, the tumor may be found on screening evaluations when the child is asymptomatic or has apparent static neurologic and/or visual deficits. Pathologic confirmation is frequently not obtained in asymptomatic patients, and when biopsies have been performed, these tumors have been found to be predominantly pilocytic (grade I) rather than fibrillary (grade II) astrocytomas.[2,4,10-12] In general, treatment is not required for incidental tumors found with surveillance scans. Symptomatic lesions or those that have radiographically progressed may require treatment.
Genomic alterations involving BRAF are very common in sporadic cases of pilocytic astrocytoma, resulting in activation of the ERK/MAPK pathway. BRAF activation in pilocytic astrocytoma occurs most commonly through a gene fusion between KIAA1549 and BRAF, producing a fusion protein that lacks the BRAF regulatory domain.[14-18] This fusion is seen in the majority of infratentorial and midline pilocytic astrocytomas, but is present at lower frequency in supratentorial (hemispheric) tumors.[14,15,19-23] Other genomic alterations in pilocytic astrocytomas that can also activate the ERK/MAPK pathway (e.g., alternative BRAF gene fusions, RAF1 rearrangements, RAS mutations, and BRAF V600E point mutations) are less commonly observed.[15,17,18,24] As expected, given the role of NF1 deficiency in activating the ERK/MAPK pathway, activating BRAF genomic alterations are uncommon in pilocytic astrocytoma associated with NF1. Presence of the BRAF-KIAA1549 fusion predicted for better clinical outcome (progression-free survival [PFS] and overall survival) in one report that described children with incompletely resected low-grade gliomas. However, other factors such as p16 deletion and tumor location may modify the impact of BRAF mutation on outcome. BRAF activation through the KIAA1549-BRAF fusion has also been described in other pediatric low-grade gliomas (e.g., pilomyxoid astrocytoma).[22,23] BRAF point mutations (V600E) are observed in nonpilocytic pediatric low-grade gliomas as well, including approximately two-thirds of pleomorphic xanthoastrocytoma cases and in ganglioglioma and desmoplastic infantile ganglioglioma.[26-28]
Molecular features of pediatric high-grade astrocytomas show some similarities to the genetic aberrations seen in adult glioblastomas that arise from preexisting lower-grade gliomas (so-called secondary glioblastoma).[29-31] These include a high incidence of TP53 mutations, a low incidence of PTEN and P16INK4A mutations, and the presence of PDGF/PDGFR overexpression. However, the IDH1 mutations that have been identified in a high proportion of adults with secondary glioblastoma are rarely seen in pediatric glioblastoma.[32,33] While the incidence of IDH1 mutations is low in children, it increases with age in the adolescent and young adult population. Mutations in histone H3.3 (H3F3A) are present in approximately one-third of non–brain stem pediatric high-grade astrocytomas,[33,34] and most of these cases also have TP53 mutations. Pediatric high-grade astrocytomas with H3F3A mutations often additionally have somatic mutations in ATRX, a gene coding for a protein involved in chromatin remodeling. The presence of the H3F3A K27M mutation occurs exclusively in diffuse high-grade pediatric astrocytomas. Diffuse intrinsic pontine gliomas show an even higher frequency of H3F3A mutations than do non–brain stem pediatric high-grade astrocytomas, with approximately three-fourths of cases showing mutations.[34,36] Diffuse intrinsic pontine gliomas show a comparably high frequency of TP53 mutations, but IDH1 and IDH2 mutations are rare. These findings suggest that a substantial proportion of pediatric high-grade astrocytomas are associated with processes required for establishing normal chromatin architecture.
The molecular profile of pediatric patients with oligodendroglioma does not demonstrate deletions of 1p or 19q, as found in 40% to 80% of adult cases. Pediatric oligodendroglioma harbors MGMT gene promoter methylation in the majority of tumors.
Gliomatosis cerebri is a diffuse glioma that involves widespread involvement of the cerebral hemispheres in which it may be confined, but it often extends caudally to affect the brain stem, cerebellum, and/or spinal cord. It rarely arises in the cerebellum and spreads rostrally. The neoplastic cells are most commonly astrocytes, but in some cases, they are oligodendroglia. They may respond to treatment initially, but overall have a poor prognosis.Prognosis
Low-grade astrocytomas (grade I [pilocytic] and grade II) have a relatively favorable prognosis, particularly for circumscribed, grade I lesions where complete excision may be possible.[40-45] Tumor spread, when it occurs, is usually by contiguous extension; dissemination to other CNS sites is uncommon, but does occur.[46,47] Although metastasis is uncommon, tumors may be of multifocal origin, especially when associated with NF1.
Unfavorable prognostic features include young age, fibrillary histology, and inability to obtain a complete resection. Elevated MIB-1 labeling index, a marker of cellular proliferative activity, is associated with shortened PFS in patients with pilocytic astrocytoma. A BRAF-KIAA fusion, found in pilocytic tumors, confers a better clinical outcome.
Oligodendrogliomas are rare in children and have a relatively favorable prognosis, with the exception of children younger than 3 years who have less than a gross total resection.High-grade astrocytomas
High-grade astrocytomas are often locally invasive and extensive and tend to occur above the tentorium.[40,43] Spread via the subarachnoid space may occur. Metastasis outside of the CNS has been reported but is extremely infrequent until multiple local relapses have occurred. Biologic markers, such as p53 overexpression and mutation status, may be useful predictors of outcome in patients with high-grade gliomas.[4,50,51] MIB-1 labeling index is predictive of outcome in childhood malignant brain tumors. Both histologic classification and proliferative activity evaluation have been shown to be independently associated with survival. Although high-grade astrocytoma carries a generally poor prognosis in younger patients, those with anaplastic astrocytoma and those in whom a gross total resection is possible may fare better.[44,53,54]Disease Presentation
Presenting symptoms for childhood astrocytomas depend not only on CNS location, but also size of tumor, rate of growth, and chronologic and developmental age of the child.References
- Louis DN, Ohgaki H, Wiestler OD, et al., eds.: WHO Classification of Tumours of the Central Nervous System. 4th ed. Lyon, France: IARC Press, 2007.
- Louis DN, Ohgaki H, Wiestler OD, et al.: The 2007 WHO classification of tumours of the central nervous system. Acta Neuropathol 114 (2): 97-109, 2007. [PUBMED Abstract]
- Smith MA, Seibel NL, Altekruse SF, et al.: Outcomes for children and adolescents with cancer: challenges for the twenty-first century. J Clin Oncol 28 (15): 2625-34, 2010. [PUBMED Abstract]
- Komotar RJ, Burger PC, Carson BS, et al.: Pilocytic and pilomyxoid hypothalamic/chiasmatic astrocytomas. Neurosurgery 54 (1): 72-9; discussion 79-80, 2004. [PUBMED Abstract]
- Tibbetts KM, Emnett RJ, Gao F, et al.: Histopathologic predictors of pilocytic astrocytoma event-free survival. Acta Neuropathol 117 (6): 657-65, 2009. [PUBMED Abstract]
- Rodriguez FJ, Scheithauer BW, Burger PC, et al.: Anaplasia in pilocytic astrocytoma predicts aggressive behavior. Am J Surg Pathol 34 (2): 147-60, 2010. [PUBMED Abstract]
- Margraf LR, Gargan L, Butt Y, et al.: Proliferative and metabolic markers in incompletely excised pediatric pilocytic astrocytomas--an assessment of 3 new variables in predicting clinical outcome. Neuro Oncol 13 (7): 767-74, 2011. [PUBMED Abstract]
- Fried I, Hawkins C, Scheinemann K, et al.: Favorable outcome with conservative treatment for children with low grade brainstem tumors. Pediatr Blood Cancer 58 (4): 556-60, 2012. [PUBMED Abstract]
- Fisher PG, Breiter SN, Carson BS, et al.: A clinicopathologic reappraisal of brain stem tumor classification. Identification of pilocystic astrocytoma and fibrillary astrocytoma as distinct entities. Cancer 89 (7): 1569-76, 2000. [PUBMED Abstract]
- Listernick R, Darling C, Greenwald M, et al.: Optic pathway tumors in children: the effect of neurofibromatosis type 1 on clinical manifestations and natural history. J Pediatr 127 (5): 718-22, 1995. [PUBMED Abstract]
- Rosai J, Sobin LH, eds.: Dysgenetic syndromes. In: Rosai J, Sobin LH, eds.: Atlas of Tumor Pathology. Third Series. Washington, DC : Armed Forces Institute of Pathology, 1994., pp 379-90.
- Allen JC: Initial management of children with hypothalamic and thalamic tumors and the modifying role of neurofibromatosis-1. Pediatr Neurosurg 32 (3): 154-62, 2000. [PUBMED Abstract]
- Molloy PT, Bilaniuk LT, Vaughan SN, et al.: Brainstem tumors in patients with neurofibromatosis type 1: a distinct clinical entity. Neurology 45 (10): 1897-902, 1995. [PUBMED Abstract]
- Bar EE, Lin A, Tihan T, et al.: Frequent gains at chromosome 7q34 involving BRAF in pilocytic astrocytoma. J Neuropathol Exp Neurol 67 (9): 878-87, 2008. [PUBMED Abstract]
- Forshew T, Tatevossian RG, Lawson AR, et al.: Activation of the ERK/MAPK pathway: a signature genetic defect in posterior fossa pilocytic astrocytomas. J Pathol 218 (2): 172-81, 2009. [PUBMED Abstract]
- Jones DT, Kocialkowski S, Liu L, et al.: Tandem duplication producing a novel oncogenic BRAF fusion gene defines the majority of pilocytic astrocytomas. Cancer Res 68 (21): 8673-7, 2008. [PUBMED Abstract]
- Jones DT, Kocialkowski S, Liu L, et al.: Oncogenic RAF1 rearrangement and a novel BRAF mutation as alternatives to KIAA1549:BRAF fusion in activating the MAPK pathway in pilocytic astrocytoma. Oncogene 28 (20): 2119-23, 2009. [PUBMED Abstract]
- Pfister S, Janzarik WG, Remke M, et al.: BRAF gene duplication constitutes a mechanism of MAPK pathway activation in low-grade astrocytomas. J Clin Invest 118 (5): 1739-49, 2008. [PUBMED Abstract]
- Korshunov A, Meyer J, Capper D, et al.: Combined molecular analysis of BRAF and IDH1 distinguishes pilocytic astrocytoma from diffuse astrocytoma. Acta Neuropathol 118 (3): 401-5, 2009. [PUBMED Abstract]
- Horbinski C, Hamilton RL, Nikiforov Y, et al.: Association of molecular alterations, including BRAF, with biology and outcome in pilocytic astrocytomas. Acta Neuropathol 119 (5): 641-9, 2010. [PUBMED Abstract]
- Yu J, Deshmukh H, Gutmann RJ, et al.: Alterations of BRAF and HIPK2 loci predominate in sporadic pilocytic astrocytoma. Neurology 73 (19): 1526-31, 2009. [PUBMED Abstract]
- Lin A, Rodriguez FJ, Karajannis MA, et al.: BRAF alterations in primary glial and glioneuronal neoplasms of the central nervous system with identification of 2 novel KIAA1549:BRAF fusion variants. J Neuropathol Exp Neurol 71 (1): 66-72, 2012. [PUBMED Abstract]
- Hawkins C, Walker E, Mohamed N, et al.: BRAF-KIAA1549 fusion predicts better clinical outcome in pediatric low-grade astrocytoma. Clin Cancer Res 17 (14): 4790-8, 2011. [PUBMED Abstract]
- Janzarik WG, Kratz CP, Loges NT, et al.: Further evidence for a somatic KRAS mutation in a pilocytic astrocytoma. Neuropediatrics 38 (2): 61-3, 2007. [PUBMED Abstract]
- Horbinski C, Nikiforova MN, Hagenkord JM, et al.: Interplay among BRAF, p16, p53, and MIB1 in pediatric low-grade gliomas. Neuro Oncol 14 (6): 777-89, 2012. [PUBMED Abstract]
- Dougherty MJ, Santi M, Brose MS, et al.: Activating mutations in BRAF characterize a spectrum of pediatric low-grade gliomas. Neuro Oncol 12 (7): 621-30, 2010. [PUBMED Abstract]
- Dias-Santagata D, Lam Q, Vernovsky K, et al.: BRAF V600E mutations are common in pleomorphic xanthoastrocytoma: diagnostic and therapeutic implications. PLoS One 6 (3): e17948, 2011. [PUBMED Abstract]
- Schindler G, Capper D, Meyer J, et al.: Analysis of BRAF V600E mutation in 1,320 nervous system tumors reveals high mutation frequencies in pleomorphic xanthoastrocytoma, ganglioglioma and extra-cerebellar pilocytic astrocytoma. Acta Neuropathol 121 (3): 397-405, 2011. [PUBMED Abstract]
- Paugh BS, Qu C, Jones C, et al.: Integrated molecular genetic profiling of pediatric high-grade gliomas reveals key differences with the adult disease. J Clin Oncol 28 (18): 3061-8, 2010. [PUBMED Abstract]
- Bax DA, Mackay A, Little SE, et al.: A distinct spectrum of copy number aberrations in pediatric high-grade gliomas. Clin Cancer Res 16 (13): 3368-77, 2010. [PUBMED Abstract]
- Ward SJ, Karakoula K, Phipps KP, et al.: Cytogenetic analysis of paediatric astrocytoma using comparative genomic hybridisation and fluorescence in-situ hybridisation. J Neurooncol 98 (3): 305-18, 2010. [PUBMED Abstract]
- Pollack IF, Hamilton RL, Sobol RW, et al.: IDH1 mutations are common in malignant gliomas arising in adolescents: a report from the Children's Oncology Group. Childs Nerv Syst 27 (1): 87-94, 2011. [PUBMED Abstract]
- Schwartzentruber J, Korshunov A, Liu XY, et al.: Driver mutations in histone H3.3 and chromatin remodelling genes in paediatric glioblastoma. Nature 482 (7384): 226-31, 2012. [PUBMED Abstract]
- Wu G, Broniscer A, McEachron TA, et al.: Somatic histone H3 alterations in pediatric diffuse intrinsic pontine gliomas and non-brainstem glioblastomas. Nat Genet 44 (3): 251-3, 2012. [PUBMED Abstract]
- Gielen GH, Gessi M, Hammes J, et al.: H3F3A K27M mutation in pediatric CNS tumors: a marker for diffuse high-grade astrocytomas. Am J Clin Pathol 139 (3): 345-9, 2013. [PUBMED Abstract]
- Khuong-Quang DA, Buczkowicz P, Rakopoulos P, et al.: K27M mutation in histone H3.3 defines clinically and biologically distinct subgroups of pediatric diffuse intrinsic pontine gliomas. Acta Neuropathol 124 (3): 439-47, 2012. [PUBMED Abstract]
- Suri V, Jha P, Agarwal S, et al.: Molecular profile of oligodendrogliomas in young patients. Neuro Oncol 13 (10): 1099-106, 2011. [PUBMED Abstract]
- Rorke-Adams LB, Portnoy H: Long-term survival of an infant with gliomatosis cerebelli. J Neurosurg Pediatr 2 (5): 346-50, 2008. [PUBMED Abstract]
- Armstrong GT, Phillips PC, Rorke-Adams LB, et al.: Gliomatosis cerebri: 20 years of experience at the Children's Hospital of Philadelphia. Cancer 107 (7): 1597-606, 2006. [PUBMED Abstract]
- Pollack IF: Brain tumors in children. N Engl J Med 331 (22): 1500-7, 1994. [PUBMED Abstract]
- Hoffman HJ, Berger MS, Becker LE: Cerebellar astrocytomas. In: Deutsch M, ed.: Management of Childhood Brain Tumors. Boston: Kluwer Academic Publishers, 1990, pp 441-56.
- Fisher PG, Tihan T, Goldthwaite PT, et al.: Outcome analysis of childhood low-grade astrocytomas. Pediatr Blood Cancer 51 (2): 245-50, 2008. [PUBMED Abstract]
- Pfister S, Witt O: Pediatric gliomas. Recent Results Cancer Res 171: 67-81, 2009. [PUBMED Abstract]
- Qaddoumi I, Sultan I, Gajjar A: Outcome and prognostic features in pediatric gliomas: a review of 6212 cases from the Surveillance, Epidemiology, and End Results database. Cancer 115 (24): 5761-70, 2009. [PUBMED Abstract]
- Wisoff JH, Sanford RA, Heier LA, et al.: Primary neurosurgery for pediatric low-grade gliomas: a prospective multi-institutional study from the Children's Oncology Group. Neurosurgery 68 (6): 1548-54; discussion 1554-5, 2011. [PUBMED Abstract]
- von Hornstein S, Kortmann RD, Pietsch T, et al.: Impact of chemotherapy on disseminated low-grade glioma in children and adolescents: report from the HIT-LGG 1996 trial. Pediatr Blood Cancer 56 (7): 1046-54, 2011. [PUBMED Abstract]
- Mazloom A, Hodges JC, Teh BS, et al.: Outcome of patients with pilocytic astrocytoma and leptomeningeal dissemination. Int J Radiat Oncol Biol Phys 84 (2): 350-4, 2012. [PUBMED Abstract]
- Stokland T, Liu JF, Ironside JW, et al.: A multivariate analysis of factors determining tumor progression in childhood low-grade glioma: a population-based cohort study (CCLG CNS9702). Neuro Oncol 12 (12): 1257-68, 2010. [PUBMED Abstract]
- Creach KM, Rubin JB, Leonard JR, et al.: Oligodendrogliomas in children. J Neurooncol 106 (2): 377-82, 2012. [PUBMED Abstract]
- Pollack IF, Finkelstein SD, Woods J, et al.: Expression of p53 and prognosis in children with malignant gliomas. N Engl J Med 346 (6): 420-7, 2002. [PUBMED Abstract]
- Rood BR, MacDonald TJ: Pediatric high-grade glioma: molecular genetic clues for innovative therapeutic approaches. J Neurooncol 75 (3): 267-72, 2005. [PUBMED Abstract]
- Pollack IF, Hamilton RL, Burnham J, et al.: Impact of proliferation index on outcome in childhood malignant gliomas: results in a multi-institutional cohort. Neurosurgery 50 (6): 1238-44; discussion 1244-5, 2002. [PUBMED Abstract]
- Finlay JL, Boyett JM, Yates AJ, et al.: Randomized phase III trial in childhood high-grade astrocytoma comparing vincristine, lomustine, and prednisone with the eight-drugs-in-1-day regimen. Childrens Cancer Group. J Clin Oncol 13 (1): 112-23, 1995. [PUBMED Abstract]
- Villano JL, Seery TE, Bressler LR: Temozolomide in malignant gliomas: current use and future targets. Cancer Chemother Pharmacol 64 (4): 647-55, 2009. [PUBMED Abstract]