Biological Therapy and Radiation Therapy in Treating Patients With Newly Diagnosed Glioblastoma Multiforme

DISEASE CHARACTERISTICS: * Histologically confirmed intracranial glioblastoma multiforme (GBM) or gliosarcoma by biopsy or resection within the past 28 days PATIENT CHARACTERISTICS: Age * 18 and over Performance status * Karnofsky 60-100% Life expectancy * More than 8 weeks Hematopoietic * WBC at least 3,000/mm\^3 * Absolute neutrophil count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 * Hemoglobin at least 10 g/dL (transfusion allowed) Hepatic * Bilirubin less than 2 times upper limit of normal (ULN) * SGOT less than 2 times ULN Renal * Creatinine less than 1.5 mg/dL Other * No significant medical illness that cannot be controlled adequately with appropriate therapy or that would compromise tolerability of study therapy * No other cancer (except nonmelanoma skin cancer or carcinoma in situ of the cervix) unless in complete remission and off all therapy for that disease for at least 3 years * No active infection * No disease that would obscure toxicity or dangerously alter drug metabolism * No other serious concurrent medical illness * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy * Not specified Chemotherapy * No prior polifeprosan 20 with carmustine implant (Gliadel wafer) * No concurrent chemotherapy Endocrine therapy * Concurrent corticosteroids to treat symptoms or prevent complications are allowed Radiotherapy * No prior radiotherapy to the brain * No concurrent stereotactic radiosurgery * No concurrent brachytherapy Surgery * See Disease Characteristics Other * No prior cytotoxic or noncytotoxic drug therapy for GBM * No prior experimental drug therapy for GBM * No other concurrent cytotoxic or noncytotoxic drug therapy for GBM * Concurrent analgesics, antiepileptics, or other drugs to treat symptoms or prevent complications are allowed