PATIENT CHARACTERISTICS: Age: 16 and over Performance status: Karnofsky 70-100% Life expectancy: At least 3 months Hematopoietic: WBC at least 3,000/mm3 Absolute neutrophil count at least 1,000/mm3 Platelet count at lest 80,000/mm3 Hemoglobin at least 10 g/dL Hepatic: Bilirubin no greater than 1.5 times normal Transaminases no greater than 1.5 times upper limit or normal (ULN) Alkaline phosphatase no greater than 3.0 times ULN Renal: Creatinine no greater than 1.5 times ULN Other: No medical conditions that would interfere with swallowing or cause excessive vomiting No second malignancy except basal and squamous cell skin cancer Not pregnant or nursing Negative pregnancy test Fertile patients must use effective barrier contraception