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|
|Astrocytic Tumors: || |
|Subependymal giant cell astrocytoma||I|
|Diffuse astrocytoma:|| |
|Oligodendroglial Tumors:|| |
|Mixed Gliomas: || |
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).