Interpretation of the TNM classification for intrahepatic cholangiocarcinoma in the American Joint Committee on Cancer cancer staging manual (8th edition)

Abstract

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver cancer with a very poor prognosis. In order to guide better clinical management of ICC patients, the American Joint Committee on Cancer (AJCC) cancer staging manual (7th edition) have established a unique TNM staging scheme for separating ICC from hepatocellular carcinoma (HCC) for the first time, and reflected a difference between risk factor of ICC and HCC. This TNM staging system for ICC has been most recently updated by the AJCC cancer staging manual (8th edition), in which T staging has been redefined without gross features, and lymph node metastasis (N1) in N staging has been grouped as stage ⅢB, but not stage Ⅳ as required by the 7th edition of AJCC cancer staging manual. In addition, region lymphatic and distant metastases have been clearly redefined by the AJCC cancer staging manual (8th edition) that also requires recovering at least 6 lymph nodes for the N staging scheme. The apparent advantages of the AJCC cancer staging manual (8th edition) for ICC pathologic staging may better stratify the prognosis of ICC patients and provide an improved guidance in clinical practice. Key words: Intrahepatic cholangiocarcinoma; TNM Classification; Eighth edition; Ameri-can Joint Committee on Cancer; Under-standing