Clinical outcomes and prognostic analysis of conversion surgery for initially unresectable biliary tract cancer: Japan-Korea collaboration study.

Background There are small scale retrospective studies showing efficacy of conversion surgery for initially unresectable biliary tract cancer (UR BTC) patients who responded long-term chemotherapy or radiation therapy. This study aimed to establish new evidence by evaluating effect of conversion surgery for UR-LA BTC from Japan and Korea. Methods Patients with initially UR BTC including intrahepatic cholangiocarcinoma (ICC), perihilar cholangiocarcinoma (PHCC), distal bile duct cancer (DBC), and gallbladder cancer (GBC) and Amplla of vater cancer (AVC) who underwent conversion surgery between January 2013 to December 2017 following chemotherapy or radiotherapy were retrospectively collected from Japanese and Korean institutes. Results A total of 91 patients, including 27 ICC, 24 PHCC, 32 GBC, 7 DBC and 1 AVC cases, were enrolled. The reasons for unresectability were local progression without distant metastasis in 66 cases (73%) and distant metastasis in 25 cases (27%). As preoperative chemotherapy, gemcitabine-based multidrug therapy was performed for 70 patients (77%), and radiation therapy was performed for 19 patients (21%). The result of evaluation of the responses using RECIST showed 5 CR cases (5%), 52 PR cases (57%), 27 SD cases (30%) and 1 PD case (1%). The median interval from the induction of treatment to surgical resection was 6.4 months. The surgical procedures comprised hepatectomy with bile duct resection in 56 cases (62%), pancreaticoduodenectomy in 7 cases (8%) and hepatopancreatoduodenectomy in 8 cases (9%). Combined vascular resection was performed 25 patients (27%). Postoperative complication over Clavian-Dindo Grade III occurred in 48 cases (53%). There were 5 mortality cases (5%). R0 resection was performed for 74 cases (81%). Pathologically CR was achieved for 13 cases (14%). Five year survival rate of initially UR-BTC patients who underwent conversion surgery after preoperative therapy was 43.9% (median survival time: 39.2 months). Conclusions Selected patients diagnosed with initially unresectable bile duct cancer are able to undergo conversion surgery and may have long-term survival after potentially curative resection.