PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: At least 3 months Hematopoietic: WBC at least 4,000/mm3 Absolute granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL ALT no greater than 1.25 times upper limit of normal (ULN) (no greater than 5 times ULN if elevation secondary to malignancy) Alkaline phosphatase no greater than 1.25 times ULN (no greater than 5 times ULN if elevation secondary to malignancy) Renal: Creatinine normal OR Creatinine clearance normal or greater than 60 mL/min Other: No medical or psychiatric condition that would preclude study No prior malignancy except: Appropriately treated localized epithelial skin or cervical cancer Remote history of other cured malignancy (at the discretion of the sponsor) Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception