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 < .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 = .002, cT2 vs cT3; P = .008 and cT3 vs cT4; P < .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.