PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: At least 3 months Hematopoietic: Absolute neutrophil count at least 2,000/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 10 g/dL Hepatic: Bilirubin no greater than 1.5 mg/dL ALT and AST no greater than 2.5 times upper limit of normal (ULN) Renal: Creatinine less than 1.5 times ULN Cardiovascular: No uncontrolled or significant cardiac disease No myocardial infarction within the past 6 months No congestive heart failure (with or without therapy) No history of atrial or ventricular arrhythmias No history of second or third degree heart block No prolonged QTc interval on electrocardiogram Pulmonary: No uncontrolled or significant pulmonary disease Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No serious uncontrolled medical disorder or active infection No dementia or altered mental status No prior or concurrent gastrointestinal disease within past 6 months No history of malabsorption No impaired oral ingestion (e.g., patients with feeding tubes)