Temozolomide and Radiation Therapy in Treating Patients With Gliomas

DISEASE CHARACTERISTICS: Histologically confirmed* supratentorial glioma of 1 of the following histologies: Astrocytoma (diffuse fibrillary, protoplasmic, or gemistocytic) Oligodendroglioma Oligoastrocytoma Note: *Histologic atypia allowed provided no other histologic features (i.e., frequent mitoses, endothelial proliferation, and/or acute necrosis) that would result in a designation of anaplastic astrocytoma, anaplastic mixed oligodendroglioma or oligoastrocytoma, or glioblastoma multiforme are present Unifocal or multifocal disease World Health Organization (WHO) grade II disease Neurofibromatosis allowed Surgical biopsy or resection for tumor tissue sampling required within the past 12 weeks Tissue block or core biopsy available for O6-methylguanine-DNA methyltransferase analysis and tissue banking Patients who have only had a stereotactic biopsy are not eligible Must have ≥ 3 of the following risk factors: Age 40 and over Largest preoperative tumor diameter ≥ 6 cm Tumor crosses the midline Astrocytoma-dominant tumor subtype Preoperative Neurological Function Status > 1 No other low-grade glioma histologies, including any of the following: Pilocytic astrocytoma Subependymal giant cell astrocytoma of tuberous sclerosis Subependymoma Pleomorphic xanthoastrocytoma Presence of a neuronal element, such as ganglioglioma Dysneuroembryoplastic epithelial tumor No high-grade glioma, including any of the following: Anaplastic astrocytoma Glioblastoma multiforme Anaplastic oligodendroglioma Anaplastic oligoastrocytoma No tumors in any non-supratentorial location, including any of the following: Optic chiasm Optic nerve(s) Pons Medulla Cerebellum Spinal cord No evidence of disease progression to spinal meninges or noncontiguous cranial meninges (i.e., leptomeningeal gliomatosis) by MRI of the spine or cerebrospinal fluid (CSF) cytology MRI of the spine or CSF cytology are not required for patients without symptoms of spinal/cranial meningeal disease progression PATIENT CHARACTERISTICS: Age 18 and over Performance status Zubrod 0-2 Life expectancy Not specified Hematopoietic Absolute neutrophil count ≥ 1,500/mm^3 Platelet count ≥ 100,000/mm^3 Hepatic Total bilirubin ≤ 1.5 mg/dL Serum glutamate oxaloacetate transaminase (SGOT) or Serum glutamate pyruvate transaminase (SGPT) ≤ 2 times normal Alkaline phosphatase ≤ 2 times normal Renal Serum creatinine ≤ 1.5 mg/dL Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No known HIV positivity No other malignancy within the past 5 years except carcinoma in situ of the cervix or nonmelanoma skin cancer No active infection PRIOR CONCURRENT THERAPY: Biologic therapy No concurrent immunotherapy or biologic therapy Chemotherapy No prior chemotherapy No other concurrent chemotherapy Endocrine therapy Not specified Radiotherapy No prior radiotherapy to the head and neck unless head and neck radiotherapy clearly excluded the brain (e.g., localized radiotherapy to the vocal cords) No prior radiotherapy to the brain No concurrent intensity modulated radiotherapy No concurrent stereotactic boost radiotherapy Surgery See Disease Characteristics Other No other concurrent investigational agents