Predicting prognosis and evaluating the benefits of adjuvant chemotherapy depending on the tumor location in intrahepatic cholangiocarcinoma: focusing on the involvement of below 2nd bile duct confluence

PURPOSE: Intrahepatic cholangiocarcinoma (ICC) has various characteristics according to anatomical, histologic classifications, and its prognoses are different. This study aimed to compare oncologic outcomes according to tumor location (second bile duct confluence) and evaluate the effect of adjuvant chemotherapy. METHODS: Clinical data of 318 patients who underwent curative resection for ICC was reviewed. Central type ICC (C-ICC) and peripheral type ICC (P-ICC) were defined when the tumor invades the intrahepatic secondary biliary confluence and when located more peripherally, respectively. RESULTS: A larger tumor size, higher rate of elevated CA 19-9 level, vascular invasion, R1 resection, advanced T stage, and lymph node metastasis were found in C-ICC. C-ICC had poorer overall survival (median, 33 months vs. 58 months; P = 0.001), and the difference was more prominent in the early stage. C-ICC had a higher recurrence rate (68.7% vs. 55.1%, P = 0.014); otherwise, there was no difference in the recurrence patterns. There were no survival benefits of adjuvant chemotherapy in the entire cohort, but there were benefits in advanced stages (T3–4, N1 stage), especially in C-ICC. CONCLUSION: C-ICC has more aggressive tumor characteristics and poor survival compared to P-ICC. Adjuvant chemotherapy seems to have survival benefits in the advanced stages, especially in the central type.