PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 90-100% Life expectancy: At least 12 months Hematopoietic: WBC greater than 3,500/mm3 Platelet count greater than 100,000/mm3 Hepatic: Bilirubin less than 1.5 mg/dL Renal: Creatinine less than 1.5 mg/dL OR Creatinine clearance greater than 60 mL/min Other: Female patients must have completed childbearing Fertile male patients must use effective contraception