Carmustine Wafers Plus Irinotecan in Treating Patients With Recurrent Supratentorial High Grade Gliomas

DISEASE CHARACTERISTICS: Histologically confirmed recurrent supratentorial glioblastoma multiforme, anaplastic astrocytoma, or gliosarcoma Must be able to undergo surgical resection At least 1 bidimensionally measurable lesion documented on Gd-MRI within 72 hours after surgical implantation of Gliadel wafers Not requiring immediate radiotherapy PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 70-100% Life expectancy: Greater than 12 weeks Hematopoietic: Absolute neutrophil count at least 1,500/mm^3 Platelet count at least 125,000/mm^3 Hematocrit at least 29% Hepatic: Bilirubin less than 1.5 times upper limit of normal (ULN) SGOT or SGPT less than 2.5 times ULN Alkaline phosphatase less than 2 times ULN Renal: BUN less than 1.5 times ULN Creatinine less than 1.5 times ULN Neurological: Must be neurologically stable Other: HIV negative No AIDS-related illness No nonmalignant systemic disease that would make patient a poor medical risk No acute infection requiring intravenous antibiotics Not pregnant or nursing Negative pregnancy test 24 hours prior to study Effective contraception required of all fertile patients PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior irinotecan At least 6 weeks since chemotherapy unless there is unequivocal evidence of tumor progression after chemotherapy Endocrine therapy: At least 1 week of nonincreasing dose of steroids prior to study Radiotherapy: At least 6 weeks since radiotherapy unless there is unequivocal evidence of tumor progression after radiotherapy No concurrent radiotherapy Surgery: Not specified