Superiority of clinical American Joint Committee on Cancer T classification for perihilar cholangiocarcinoma

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