PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Zubrod 0-2 Life expectancy: Greater than 12 weeks Hematopoietic: Neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than upper limit of normal (ULN) SGOT and/or SGPT no greater than 2.5 times ULN if alkaline phosphatase less than ULN, OR alkaline phosphatase no greater than 4 times ULN if SGOT and/or SGPT less than ULN Renal: Creatinine clearance at least 50 mL/min Other: No concurrent illness that would effect assessment of this study Not pregnant or nursing Effective contraception required of all fertile patients