<qa>  How many weeks of chemotherapy is the duration of the treatment?The eligibility criteria are patients with advanced or metastatic carcinoma of the biliary tract who are not candidates for curative surgical treatment; good performance status; no prior chemotherapy; clinical measurable tumor; good organ function and good compliance. Each cycle of chemotherapy consists of 4 weeks. On days 1, 8 and 15, gemcitabine will be given by 30-minute intravenous infusion and 5-FU and leucovorin by 24-hour continuous intravenous infusion. The dose of gemcitabine will be 1000 mgm2. The doses of 5-FU will be 2000 mgm2 and leucovorin, 300 mgm2. Treatment will continue until disease progresses or prohibitive toxicity develops. For patients with complete response CR, chemotherapy will continue for 3 additional courses after the documentation of CR. Estimated time for patient accrual is 3 years. 