PATIENT CHARACTERISTICS: Age: Under 70 Performance status: WHO 0-2 Life expectancy: Not specified Hematopoietic: Absolute neutrophil count greater than 2,000/mm3 WBC greater than 3,500/mm3 Platelet count greater than 100,000/mm3 Hepatic: Bilirubin no greater than 1.46 mg/dL Transaminases less than 2 times upper limit of normal Renal: Creatinine no greater than 1.70 mg/dL Creatinine clearance greater than 60 mL/min Other: No prior or concurrent malignancies at other sites with the exception of adequately treated in situ carcinoma of the cervix or basal and squamous carcinoma of the skin Not pregnant or nursing Negative pregnancy test 24 hours prior to commencing temozolomide