PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0 or 1 Life expectancy: Not specified Hematopoietic: 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 no greater than 2.5 times ULN Renal: Creatinine no greater than 1.5 times ULN Other: Not pregnant or nursing Fertile patients must use effective contraception No active second malignancy except nonmelanomatous skin cancer Not considered an active second malignancy if: Therapy has been completed Less than 30% risk of relapse according to the physician No malabsorption syndrome