PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Greater than 8 weeks Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 75,000/mm3 (transfusion independent) Hepatic: Bilirubin no greater than 2 times upper limit of normal (ULN) AST/ALT no greater than 2 times ULN Renal: Creatinine no greater than 1.5 times ULN Calcium no greater than 12 mg/dL Other: Not pregnant or nursing Fertile patients must use effective contraception No life threatening illness unrelated to the tumor No concurrent serious infection No prior malignancy within the past 3 years except nonmelanoma skin cancer or carcinoma in situ of the cervix Must be capable of swallowing intact medication capsules No medical or psychiatric condition that would prevent written informed consent