Prognostic comparison of the 7th and 8th editions of the American Joint Committee on Cancer staging system for intrahepatic cholangiocarcinoma

Abstract Background Several important changes were made to the 8th edition of the American Joint Committee on Cancer ( AJCC ) tumor staging system for intrahepatic cholangiocarcinoma ( ICC ). We assessed the prognostic impact of this new tumor staging system compared to the 7th edition. Methods A retrospective single‐institution study was performed with 626 patients who underwent R0 resection for ICC over 20‐year period. Results Anatomical resection and concurrent bile duct resection were performed in 571 (91.2%) and 62 (9.9%) patients, respectively. Cumulative tumor recurrence and patient survival rates were 40.6% and 73.3% at 1 year; 66.7% and 43.8% at 3 years; 73.6% and 30.4% at 5 years; and 74.4% and 20.3% at 10 years, respectively. Independent prognostic factors for tumor recurrence and patient survival were multiple tumors, carbohydrate antigen 19‐9 >200 U/ml, tumor size >5 cm, direct invasion to extrahepatic structure, and lymph node metastasis. For tumor‐node‐metastasis stages in the 7th versus the 8th editions, concordance index was 0.615 and 0.625 for tumor recurrence and 0.626 and 0.628 for patient survival, respectively. Conclusions The 8th edition of the AJCC staging system appears to provide high prognostic contrast for T stage categories, except for T3. However, overall prognostic performance of the 8th edition was not markedly improved over the 7th edition.