PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: At least 12 weeks Hematopoietic: WBC at least 3500/mm3 Absolute neutrophil count at least 1500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL AST and ALT no greater than 3 times upper limit of normal Renal: Creatinine no greater than 1.5 mg/dL OR Creatinine clearance at least 60 mL/min Other: No other significant, uncontrolled underlying medical or psychiatric condition No serious active infection Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception Neurologically stable No other prior malignancy within past 5 years except curatively treated nonmelanomatous skin cancer