Evaluation of Treatment Outcomes for Distal Cholangiocarcinoma Based on the 7th Edition of the Japanese Classification of Biliary Tract Carcinoma

Abstract

In 2021, the 7th edition of the Classification of Biliary Tract Carcinoma revised the T classification for distal cholangiocarcinoma, replacing the anatomical depth-based system with one based on depth of invasion (DOI) or invasive tumor thickness (ITT). This study evaluated 45 patients who underwent surgical resection for distal cholangiocarcinoma at our institution, comparing the T classifications of the 7th, 6th, and 5th editions. The 7th edition increased the number of cases classified as T1 or T2. Notably, favorable 5-year survival rates were observed even in node-positive cases when DOI or ITT was <5mm. These results suggest that DOI- or ITT-based classification better reflects tumor progression and prognosis than the previous system. Both DOI and ITT were useful prognostic indicators, supporting the validity of the 7th edition T classification for distal cholangiocarcinoma.