Survival outcomes of combined hepatocellular‐cholangiocarcinoma compared with intrahepatic cholangiocarcinoma: A SEER population‐based cohort study

BACKGROUND: Combined hepatocellular‐cholangiocarcinoma (CHC) is a heterogeneous group of primary liver cancers characterized by the coexistence of both hepatic and biliary cellular contents. The aim of this study was to compare CHC and intrahepatic cholangiocarcinoma (ICC) and investigate the treatment and survival of patients with CHC. METHODS: Data on CHC and ICC, including clinicopathological characteristics, treatments, and survival outcomes were extracted from the SEER database between 2004 and 2016. Univariate and multivariate analyses of all data were performed to identify the risk factors associated with survival outcomes. The overall survival (OS) rates of CHC patients who underwent hepatic resection (HR) or liver transplantation (LT) were also assessed before and after propensity score matching. RESULTS: A total of 1066 consecutive patients who had been diagnosed with CHC (n = 286) or ICC (n = 780) were identified. The mean age of the CHC cohort was 60.8±10.7 years old. Among the CHC group, a large proportion of the patients were men and of White ethnicity (73.1% and 71.3%, respectively). The majority of tumors were poorly differentiated (37.8%), while the most common AJCC stage at presentation was stage I (31.4%). Multivariable analysis of all CHC patients revealed that only tumor size, M(1) stage, AJCC stage IIIC, AJCC stage IV, surgery, and chemotherapy were significantly associated with OS. The OS was comparable with the ICC in the initial 36 months and better in the subsequent follow‐up after treatment. Surgery was associated with better survival outcomes, whether in the early or advanced stages. Regarding the specific types of surgery, the OS rates were similar in selected patients following HR or LT. CONCLUSION: In patients with CHC, surgical intervention resulted in better long‐term survival outcomes than nonsurgical treatments. The OS rate of CHC patients compared with that of ICC patients was discriminated before and after a 3‐year follow‐up.