Abstract
In November 2013, the Japanese Society of Hepato-Biliary-Pancreatic Surgery published the 6th edition of the Japanese classification of the biliary tract cancers, which was revised in 10 years. The primary aim of this revision is to provide all clinicians and researchers with a common language of cancer staging at an international level. Therefore, the same stage groupings as those in the UICC/AJCC staging system are basically adopted. The contiguous extent of the primary tumor is also identical in principle with that in the UICC/AJCC staging system, although slight modifications, which are believed to be important to optimize the future staging system, are proposed as the "Japanese rules". Japanese traditional lymph node grouping is eliminated, while regional lymph nodes of each carcinoma are defined according to the UICC/AJCC staging system. Surgical margin status is regulated solely by the absence or presence of residual tumor macroscopically and microscopically. Residual tumor after surgical resection is indicated by the R classification. Intraepithelial residual tumors are classified as R1, but the designator "cis" should be supplemented to differentiate from residual invasive tumors. Some parts of the WHO classification are adopted for histological classification.
