PATIENT CHARACTERISTICS: Age: 15 and over Performance status: Any status Life expectancy: At least 2 years Hematopoietic: Not specified Hepatic: Bilirubin no greater than 1.5 times normal (unless further elevation is directly attributable to malignancy) Renal: Creatinine no greater than 1.5 times normal (unless further elevation is directly attributable to malignancy) Cardiovascular: No uncontrolled or severe cardiovascular disease, e.g.: No myocardial infarction within the past 6 months No congestive heart failure Other: HIV negative No active, uncontrolled bacterial, viral, or fungal infection No active, uncontrolled duodenal ulcer No other serious medical illness No serious psychiatric condition that would preclude informed consent or protocol compliance No second malignancy within 5 years except: Curatively treated carcinoma in situ of the cervix Curatively treated basal cell carcinoma Not pregnant Effective contraception required of fertile patients