Trial of S-1 Plus Cisplatin (SP) Versus Gemcitabine Plus Cisplatin (GP) in Advanced Biliary Tract Adenocarcinoma

Inclusion Criteria: 1. Pathologically proven biliary adenocarinoma 2. Age \> 18 3. Evaluable disease 4. ECOG performance status of 2 or better 5. No prior exposure to chemotherapy, but adjuvant chemotherapy (or chemoradiotherapy) completed 6 moths or more before study enrollment is allowed 6. Adequate bone marrow function A. WBCs \> 4,000/µL, absolute neutrophil count \[ANC\]\>1,500/µL B. Hemoglobin \>9.0 g/dL C. Platelets \> 100,000/µL 7. Adequate kidney function (creatinine\<1.5 mg/dL) 8. Adequate liver function (bilirubin\<1.5 mg/dL \[\< 2.5 mg/dL for obstructive jaundice with adequately decompressed bile duct obstruction\], transaminases levels\<3 times the upper normal limit, and serum albumin of \>2.5 mg/dL) 9. No serious medical or psychological condition that would preclude study treatment 10. Willingness and ability to comply with scheduled visits, treatment plans, laboratory tests, and other study procedures Exclusion Criteria: 1. Other tumor type than adenocarcinoma 2. Evidence of GI bleeding or GI obstruction 3. Presence or history of CNS metastasis 4. Pregnancy or breastfeeding 5. Other serious illness or medical conditions 6. Axial skeletal radiotherapy within 6 months 7. Neuropathy grade 2 or worse