PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: At least 3 months Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin less than 1.5 mg/dL ALT and AST less than 2 times upper limit of normal (ULN) (unless clearly related to hepatic metastases) Renal: Creatinine less than 1.5 times ULN Other: No other serious uncontrolled medical disorder or active infection that would preclude study No dementia or altered mental status that would preclude study Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 10 weeks after study