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