Improved prognostic predictability of the latest Japanese TNM Classification in patients undergoing resection for distal cholangiocarcinoma

In March 2021, the Japanese TNM Classification for Cancer of the Biliary Tract (JCCB) was revised. This study aimed to validate the 7th edition of JCCB based on long-term outcomes after resection for distal cholangiocarcinoma (DCC). We retrospectively reviewed 107 patients with resected DCC without distant metastasis between 2007 and 2019. Survival curves according to TNM factors were compared between the 6th and 7th editions. The 5-year overall survival (OS) and recurrence-free survival rate (RFS) were 43.4% and 35.5%, respectively. Significant differences in OS were observed between T categories in the 7th edition (T1 <i>vs.</i> T2, <i>p</i> = 0.049; T2 <i>vs.</i> T3, <i>p</i> = 0.027), but not in the 6th. The N classification also showed better prognostic discrimination in both editions, with more refined stratification in the 7th. Stage grouping in the 6th edition failed to show significant OS differences, while the 7th edition demonstrated clear stratification (<i>e.g.</i>, Stage I <i>vs.</i> IIA, <i>p</i> = 0.0274; StageⅡA <i>vs.</i> StageⅡB, <i>p</i> = 0.0043; StageⅡB <i>vs.</i> StageⅢA, <i>p</i> = 0.0108). These findings indicate that the revised T and N classifications in the 7th edition more accurately reflect postoperative prognosis for resected DCC. Overall, our results support the clinical validity and improved prognostic utility of the 7th edition compared with the 6th edition.