Histological complete response in a patient with advanced biliary tract cancer treated by gemcitabine/cisplatin/S-1 combination chemotherapy: A case report.

A 68-year-old woman was referred to our hospital with increased levels of biliary enzymes. On imaging, the patient was diagnosed with unresectable intrahepatic biliary tract cancer (BTC) with invasion of the portal vein and para-aortic lymph node metastasis (cT3N1M1, cStage IVb) and underwent endoscopic biliary drainage for the biliary stricture prior to therapy. The patient was subsequently enrolled in a phase III randomized trial (UMIN000014371/NCT02182778) and randomly assigned to receive gemcitabine/cisplatin/S-1 (GCS) combination therapy intravenously at doses of 1,000 or 25 mg/m(2) on day 1 and orally twice daily at a dose of 80 mg/m(2) on days 1-7 every 2 weeks. After 12 cycles of scheduled therapy without uncontrollable adverse effects, the patient achieved a good partial response with chemotherapy. Computed tomography (CT) revealed a marked reduction of the primary and metastatic lesions. In addition,(18)F-fluorodeoxyglucose-positron emission tomography/CT revealed diminishing abnormal uptake and no macroscopic evidence of factors adversely affecting tumor resectability. Therefore, the patient underwent extended right hepatic lobectomy, lymph node dissection and left hepaticojejunostomy. Finally, histological examination of the resected tissues revealed no residual cancer cells, suggesting a pathologically complete response. We herein present the case of a patient with intrahepatic BTC who achieved a pathologically complete response following combination chemotherapy with GCS.