OBJECTIVE : This study aimed at investigating the efficacy of percutaneous transhepatic biliary stenting (PTBS) combined with 125I seeds intracavitary irradiation in the treatment of extrahepatic cholangiocarcinoma (EHC) and to preliminarily explore the prognostic values of inflammation-based scores in these patients. METHODS : A total of 113 clinically/pathologically diagnosed cases of EHC who received PTBS combined with 125I seeds implantation were retrospectively analyzed. The postoperative changes of clinical symptoms and serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total serum bilirubin (TBIL), direct bilirubin (DBIL), and albumin (ALB) were observed. Preoperative clinical data were extracted to calculate inflammation-based scores, including systemic immune-inflammation index (SII), neutrophil-to-lymphocyte ratio (NLR), and platelets-to-lymphocyte ratio (PLR). Kaplan-Meier survival curves and Cox regression analyses were used to evaluate the prognostic significance of inflammation-based scores. RESULTS : After operation, clinical symptoms such as jaundice and fever significantly improved in all patients. At 1 month and 3 months postoperatively, serum levels of ALT, AST, ALP, TBIL, and DBIL significantly reduced, and ALB significantly increased, compared with preoperative values. The median survival time of the patients was 12 months and the 1-year survival rate was 56.8%. Univariate analysis revealed that factors related to overall survival were CA19-9, TBIL, ALB, SII, and NLR. Multivariate analysis further identified SII and NLR as independent prognostic models. CONCLUSIONS : The combination of PTBS and 125I seeds intracavitary irradiation is an effective palliative treatment for advanced EHC. Elevated SII and NLR can be used to predict poor survival.