Temozolomide in Treating Patients With Recurrent or Progressive Malignant Glioma

DISEASE CHARACTERISTICS: * Histologically proven recurrent or progressive malignant glioma of one of the following types: * Anaplastic oligodendroglioma or oligoastrocytoma * Anaplastic astrocytoma * Glioblastoma multiforme (stratum closed to accrual 11/30/01) * Patients who have failed radiotherapy are eligible * Measurable disease by CT scan or MRI PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * Karnofsky 70-100% Life expectancy: * At least 12 weeks Hematopoietic: * Absolute neutrophil count greater than 1,500/mm\^3 * Platelet count greater than 100,000/mm\^3 * Hemoglobin greater than 10 g/dL Hepatic: * SGOT or SGPT less than 3 times upper limit of normal (ULN) * Alkaline phosphatase less than 2 times ULN (if greater than 2 times ULN then a gamma glutamyl transferase test must be performed) Renal: * BUN less than 1.5 times ULN * Creatinine less than 1.5 times ULN Other: * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective barrier contraception * No other serious concurrent infection or other medical illness that would preclude study entry * No frequent vomiting or partial bowel obstruction * HIV negative * No AIDS-related illness * No other concurrent malignancy except carcinoma in situ of the cervix or basal cell skin cancer PRIOR CONCURRENT THERAPY: Biologic therapy: * No concurrent epoetin alfa Chemotherapy: * At least 6 weeks since other prior chemotherapy Endocrine therapy: * Not specified Radiotherapy: * See Disease Characteristics * At least 3 months since prior radiotherapy (exceptions allowed for recurrent/progressive disease at discretion of primary investigator) Surgery: * Recovered from prior surgery Other: * No other concurrent investigational agents * Concurrent anticonvulsant therapy allowed