PATIENT CHARACTERISTICS: Age: 16 to 69 Performance status: ECOG 0-2 Life expectancy: At least 3 months Hematopoietic: WBC at least 3,000/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.4 mg/dL Renal: Creatinine no greater than 1.3 mg/dL Creatinine clearance at least 60 mL/min Other: Not pregnant or nursing Fertile patients must use effective contraception No active or uncontrolled infection No other disease, including malignancy, that would preclude study No neurologic or psychiatric disturbance that would preclude study