PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-3 Life expectancy: Not specified Hematopoietic: Absolute granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Not specified Renal: Creatinine normal Other: Not pregnant or nursing Fertile patients must use effective contraception No prior malignancies except curatively treated carcinoma in situ of the cervix or nonmelanoma skin cancer No other serious illness or medical condition No active uncontrolled infection No history of neurologic or psychiatric disorder