PATIENT CHARACTERISTICS: Age: Not specified 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: Ability to swallow and/or receive enteral medications via gastrostomy feeding tube No intractable nausea or vomiting No other prior malignancy within the past 5 years except adequately treated basal or squamous cell skin cancer, carcinoma in situ of the cervix, or stage I or II cancer in remission Not pregnant or nursing Fertile patients must use effective contraception