PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Greater than 12 weeks Hematopoietic: Platelet count at least 100,000/mm3 Hemoglobin greater than 10.0 g/dL WBC at least 3,500/mm3 OR Absolute neutrophil count at least 1,500/mm3 Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) SGOT/SGPT no greater than 1.5 times ULN Alkaline phosphatase less than 2 times ULN Renal: Calcium less than ULN Creatinine or BUN less than 1.5 times ULN OR Creatinine clearance greater than 60 mL/min Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or fully excised and/or treated stage I cancer currently in complete remission No nonmalignant systemic disease rendering patient a poor medical risk No acute infection requiring IV antibiotics HIV negative No AIDS-related illness No frequent vomiting or medical condition that could interfere with oral medication intake (e.g., partial bowel obstruction)