LAUSR

BACKGROUND Clinical tumor staging is essential information for making a therapeutic decision in cancer. This study aimed to identify the optimal tumor classification system for predicting resectability and survival probability in perihilar cholangiocarcinoma. METHODS Patients who were treated for perihilar cholangiocarcinoma between 2009 and 2018 were enrolled. Local tumor extension was staged radiologically according to a diameter-based classification system in addition to the AJCC, Blumgart, and Bismuth systems. Survival and resectability were compared between T subgroups, and the discriminability of the four systems was assessed with Harrell's concordance index (C-index). RESULTS Among 702 study patients, 559 (80.0%) underwent laparotomy, 489 (70.0%) of whom underwent resection. The resectability significantly decreased for more advanced tumors in all systems (P<0.001); the AJCC system had the greatest discriminability for resectability (area under the curve 0.721). Overall survival at 5 years was 69.9% for AJCC cT1, 45.8% for cT2, 31.8% for cT3, and 15.3% for cT4 tumors (cT1 vs. cT2; P=0.002, cT2 vs. cT3; P=0.008 and cT3 vs. cT4; P<0.001). The AJCC system had the largest C-index of 0.627. CONCLUSIONS The AJCC T system was the optimal classification system for predicting resectability and survival in perihilar cholangiocarcinoma.