Macroscopic types of intrahepatic cholangiocarcinoma and the eighth edition of AJCC/UICC TNM staging system

// Ze-Wu Meng 1, 2, * , Wei Pan 1, 2 , Hai-Jie Hong 1, 2 , Jiang-Zhi Chen 1, 2 and Yan-Ling Chen 1, 2 1 Department of Hepatobiliary Surgery, Fujian Medical University Union Hospital, Fuzhou, Fujian 350001, People’s Republic of China 2 Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, Fuzhou, Fujian 350001, People’s Republic of China * First author Correspondence to: Yan-Ling Chen, email: drchenyl@126.com Keywords: intrahepatic cholangiocarcinoma, macroscopic type, TNM classification, clinicopathological characteristics, prognosis Received: June 08, 2017 Accepted: August 26, 2017 Published: September 15, 2017 ABSTRACT The prognosis of patients with intrahepatic cholangiocarcinoma (ICC) is undefined among the different macroscopic types. This study evaluated the viability of the American Joint Committee on Cancer (AJCC) 8th edition staging classification for different macroscopic types. Utilizing the Surveillance, Epidemiology, and End Results (SEER) database, we enrolled a total of 2,679 eligible patients with an estimated 199 periductal infiltrating type of ICC (ICC-PI) patients and 2,480 mass-forming type of ICC (ICC-MF) patients. After conducting a multivariate Cox analysis, we found that the AJCC 8th edition staging system was suitable for ICC-MF patients but not for ICC-PI patients according to cancer-specific survival (CSS) and overall survival (OS). The main reason was the similar hazard ratio (HR) between the ICC-PI patients with stage I and stage II disease according to CSS (HR:0.969, P = 0.949) and OS (HR:0.832, P = 0.703). Moreover, we found that ICC-PI patients in AJCC stage I had a similar HR as ICC-MF patients in AJCC stage II according to CSS (HR: 1.208, P = 0.475) and OS (HR:1.206, P = 0.456). Therefore, we suggested that ICC-PI patients may be defined as T2, which is classified as stage II disease. This suggestion for the AJCC 8th edition staging system would be more suitable for different macroscopic types of ICC but requires further verification in prospective clinical trials.