DISEASE CHARACTERISTICS: Histologically proven newly diagnosed CNS tumors Eligible tumor types: Glioblastoma multiforme (WHO grade IV) Anaplastic astrocytoma (WHO grade III) Anaplastic oligodendroglioma (WHO grade III) Mixed anaplastic oligoastrocytoma (WHO grade III) Incompletely resected ependymoma Diffusely intrinsic pontine or medullary glioma Histology requirement waived OR Histologically proven recurrent or progressive CNS tumors Eligible tumor types: Same as above plus oligodendroglioma (WHO grade II) No brainstem tumors arising from the cervicomedullary region or midbrain without histologic proof of malignancy No supratentorial low grade astrocytomas (WHO grade I or II)