Comparison of the 7th and 8th editions of the American Joint Committee on Cancer Staging Systems for perihilar cholangiocarcinoma

Background: The performances of the American Joint Committee on Cancer staging systems of the 7th and 8th edition were compared using a cohort of patients undergoing surgery for perihilar cholangiocarcinoma at 2 tertiary referral Italian hepatobiliary centers. Methods: The American Joint Committee on Cancer 7th and 8th edition staging systems were used to classify 214 patients who underwent surgery for perihilar cholangiocarcinoma. The performances of the 2 staging systems were compared using the concordance index. Results: Using the American Joint Committee on Cancer 7th edition staging system, we found that the 5-year overall survival for stages I, II, and IVa was 71%, 34%, and 34%, while no patients in stages IIIa, IIIb, and IVb survived 5 years. In comparison, when the American Joint Committee on Cancer 8th edition staging system was used, the 5-year overall survival was 71% and 35% in stages I and II, resulting in 23%, 19%, and 22% in stages IIIa, IIIb, and IIIc, respectively. Of note, no patients in stages IVa and IVb survived 5 years. The American Joint Committee on Cancer 8th edition staging system had a slightly better discriminatory ability with a concordance index of 0.624 compared with 0.619 for the American Joint Committee on Cancer 7th edition. Conclusion: The newly released classification American Joint Committee on Cancer 8th edition staging system demonstrated a poor to moderate ability to predict prognosis of patients undergoing liver resection for perihilar cholangiocarcinoma, which was only slightly better than the previous edition. Further refinements are needed to improve the prognostic ability of the American Joint Committee on Cancer staging system for perihilar cholangiocarcinoma.