PATIENT CHARACTERISTICS: Age: Age greater than or equal to 18 years Performance status: Karnofsky 70-100% Life expectancy: Expected survival greater than 12 weeks Hematopoietic: No inadequate bone marrow function within 2 weeks prior to randomization as evidenced by the following: Absolute neutrophil count less than 2000/mm3 Platelet count less than 100,000/mm3 Hepatic: No inadequate hepatic function within 2 weeks prior to randomization as evidenced by the following: Total bilirubin greater than 1.5 times upper limit of normal (ULN) AST or ALT greater than 3 times ULN (greater than 5 times ULN if liver metastases is documented) Renal: No inadequate renal function within 2 weeks prior to randomization as evidenced by the following: Creatinine clearance less than 50 mL/min Other: Adequate IV access to receive gemcitabine infusion Capable of swallowing intact study medication capsules Capable of giving informed consent Capable of following instructions or having a daily caregiver who assumes responsibility for administering study medication and completing medication diaries No life threatening illness (unrelated to tumor) No women of childbearing potential unless using an acceptable method of contraception, or who are pregnant or nursing