Modification of the AJCC/UICC 8th edition staging system for intrahepatic cholangiocarcinoma: proposal for an alternative staging system from cholangiocarcinoma-prevalent Northeast Thailand

Background Intrahepatic cholangiocarcinoma (iCCA) arises from bile ducts within the liver. Thailand has the highest incidence of CCA worldwide, with a high mortality rate. Early diagnosis and accurate prognostic stratification can improve overall survival. We aim to modify the AJCC/UICC 8th edition staging system for iCCA by creating the Khon Kaen University (KKU) staging system for more precise patient stratification and prognostic prediction. Methods A total of 298 iCCA patients who underwent hepatectomy were included in this retrospective study at the Srinagarind Hospital, Khon Kaen University, Thailand. Univariate and multivariate analysis were performed to examine survival rate, hazard ratio, and prognostic factors. Results Univariate and multivariate analysis of the cohort showed that growth patterns, histological type, histological grade, lymph node metastasis and distant metastasis were independent prognostic factors when compared to the respective reference groups. The 8th AJCC staging system incorporated growth patterns into the KKU staging system. This model modified AJCC stages I, II, and III for better prediction of patient survival. Conclusion Growth patterns were incorporated to improve the 8th AJCC staging system for prognostication of iCCA patients in Northeast Thailand. We propose the KKU staging system as an alternative model for iCCA staging to augment the accuracy of survival prognostication.