PATIENT CHARACTERISTICS: Age: 18 and over Performance Status: ECOG 0-2 Life Expectancy: Not specified Hematopoietic: WBC at least 2,500/mm3 Absolute neutrophil count at least 1,250/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin less than 1.5 times upper limit of normal (ULN) SGOT less than 1.5 times ULN Renal: Creatinine clearance at least 50 mL/min Cardiovascular: No New York Heart Association class III or IV congestive heart failure Other: Not pregnant or nursing Fertile patients must use effective contraception No uncontrolled peptic ulcer disease No inflammatory bowel disease No history of significant autoimmune disease (rheumatoid arthritis or systemic lupus erythematosus)