Brain and other central nervous system (CNS) cancers include a variety of histopathologic subtypes, but the most common, by far, are gliomas. These tumors, which arise from the glial cells that surround and support neurons, include astrocytoma, glioblastoma, oligodendroglioma, oligoastrocytoma, and ependymoma. Medulloblastoma, another neuroepithelial cancer, is relatively common in children but rare in adults. Brain cancers in children typically arise in the cerebellum, whereas brain cancers in adults are more likely to occur in the cerebral hemispheres [1]. In adults, older age at diagnosis of brain cancer is associated with higher tumor grade and poorer prognosis. Indeed, glioblastoma is among the most lethal of all cancers. Molecular studies of brain cancers reveal still greater heterogeneity of tumor types than is apparent based on histopathology, and efforts are underway to develop a molecular classification of brain cancer.