PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Zubrod 0-1 Life expectancy: Not specified Hematopoietic: Absolute granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) SGOT or SGPT no greater than 2.5 times ULN Renal: Creatinine no greater than 2.0 mg/dL Other: Not pregnant or nursing Fertile patients must use effective contraception Must be able to swallow or receive enteral medications through gastrostomy feeding tube No intractable nausea or vomiting No other prior malignancy for the past 5 years except adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or any adequately treated stage I or II cancer in complete remission