PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 60-100% Life expectancy: Not specified Hematopoietic: WBC at least 3,500/mm3 Platelet count at least 100,000/mm3 Hepatic: SGOT and SGPT no greater than 2.5 times upper limit of normal Renal: Creatinine no greater than 2.0 mg/dL Creatinine clearance greater than 61 mL/min Other: No history of any underlying medical or psychiatric illness Not pregnant or nursing Effective contraception required of all fertile patients