Evaluation of the AJCC 8th Edition Staging System for Pathologically Versus Clinically Staged Intrahepatic Cholangiocarcinoma (iCCA): a Time to Revisit a Dogma? A Surveillance, Epidemiology, and End Results (SEER) Analysis

Background Recently, the AJCC has released its 8th edition changes to the staging system for intrahepatic cholangiocarcinoma (iCCA). This study sought to validate the proposed changes to the 8th edition of AJCC system for T and N classification of iCCA using a population-based data set. Methods Using the Surveillance, Epidemiology, and End Results (SEER) database (1998–2013), patients undergoing resection or non-surgical management for non-metastatic iCCA were identified. Overall survival was estimated using the Kaplan-Meier method and compared using log-rank tests. Concordance indices (c-indices) calculated from Cox proportional hazards models were calculated to evaluate discriminatory power. Results The study included 2630 patients resected (37%) or non-surgically managed (63%) for iCCA. Nodal staging was performed in 56%, of whom 31% had positive nodes. For all patients with iCCA, the median 5-year survival by AJCC T classification for T1a, T1b, T2, T3, and T4 was 32, 21, 14, 10, and 10 months, respectively ( p