PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1500/mm3 Platelet count at least 125,000/mm3 Hepatic: Bilirubin no greater than upper limit of normal (ULN) SGOT no greater than 2.5 times ULN (less than 3 times ULN if liver metastases) Renal: Creatinine no greater than ULN Other: Not pregnant or nursing Fertile patients must use effective contraception