Adjuvant Palliative Capecitabine and Gemcitabine in Treating Patients With Locally Advanced or Metastatic Biliary Tract Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed biliary tract cancer Locally advanced, unresectable, or metastatic disease Metastatic adenocarcinoma with clinical documentation of gallbladder or bile tree involvement with no evidence of another primary adenocarcinoma allowed Measurable or nonmeasurable disease Treatable biliary duct obstruction must be relieved by either internal endoscopic drainage/stenting or palliative bypass surgery before study entry Symptomatic biliary tract cancer and has at least 1 of the following: Karnofsky 60-80% Baseline analgesic consumption at least 10 mg of morphine equivalents per day Baseline pain intensity score of at least 20 mm out of a possible 100 mm No prior or concurrent CNS metastasis PATIENT CHARACTERISTICS: Age 18 to 80 Performance status See Disease Characteristics Karnofsky 60-100% Life expectancy Not specified Hematopoietic Neutrophil count at least 1,500/mm^3 Platelet count at least 100,000/mm^3 Hemoglobin at least 10.0 g/dL Hepatic Bilirubin no greater than 4 times upper limit of normal (ULN) Alkaline phosphatase no greater than 5 times ULN AST and ALT no greater than 5 times ULN Renal Creatinine clearance greater than 50 mL/min Cardiovascular No uncontrolled cardiovascular disease Gastrointestinal Able to ingest oral medication No malabsorption syndrome No intractable nausea and/or vomiting No partial small bowel obstruction Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 1 year after study participation No active autoimmune disease No uncontrolled diabetes No known hypersensitivity to fluorouracil No known dihydropyrimidine dehydrogenase deficiency No definitive contraindication to corticosteroids No prior significant neurologic or psychiatric disorders (e.g., psychotic disorders, dementia, or seizures) that would preclude understanding or providing informed consent No prior severe reaction to fluoropyrimidine therapy No psychiatric disorder, cognitive dysfunction, or language problem that would preclude filling out the quality of life questionnaire or patient diary No other serious underlying medical condition that would preclude study participation No other malignancy within the past 5 years except nonmelanoma skin cancer or adequately treated carcinoma in situ of the cervix PRIOR CONCURRENT THERAPY: Biologic therapy No prior biologic therapy No prior immunotherapy Chemotherapy No prior chemotherapy for advanced/metastatic disease No prior palliative chemotherapy Endocrine therapy No concurrent megestrol Radiotherapy More than 4 weeks since prior radiotherapy No concurrent radiotherapy Treatment of a single painful lesion allowed Surgery See Disease Characteristics Prior Whipple procedure allowed Prior duodenal bypass allowed No concurrent endoscopic or external biliary drainage as a consequence of progressive malignant bile duct obstruction Drainage as a consequence of nonmalignant bile duct obstruction allowed Other More than 30 days since prior treatment within a clinical study No other concurrent anticancer drugs No other concurrent investigational drugs No concurrent sorivudine or its chemically-related analogues (e.g., lamivudine)