Outcomes of patients with intrahepatic cholangiocarcinoma with a focus on the interaction between tumor stage and age on mortality over the past decade.

e16201 Background: Intrahepatic cholangiocarcinoma(iCCA) is the second most prevalent liver tumor and originates from the epithelial cells of the bile duct . The purpose of this study is to assess to the extent independent prognostic factors influence mortality in iCCA. We also investigated the clinical characteristics and survival outcomes of patients with iCCA between 2010 and 2017. Methods: Data from the Surveillance, Epidemiology, and End Results (SEER) database provided information on 5083 iCCA patients in the USA, between 2010 and 2017. Demographics, clinical features, overall mortality (OM), cancer-specific mortality (CSM), and the interaction between age and tumor stage were analyzed. Variables with p 1 indicating adverse prognostic factors. Results: Multivariate Cox proportional hazard regression analyses showed higher OM in males (HR = 1.19), metropolitan counties with 250,000 population (HR = 1.15), and lower in the age groups 40-59 (HR = 0.58) and 60-79 (HR = 0.65). Patients who underwent radiation therapy (HR = 0.78), chemotherapy (HR = 0.54), and surgery (HR = 0.29) had lower OM. Similarly, CSM was higher in males (HR = 1.17) and metropolitan counties (HR = 1.18), but lower in age groups 40-59 (HR = 0.52) and 60-79 (HR = 0.57). Interaction analysis revealed higher OM in stage III tumors with lymph node involvement aged 40-59 (HR = 2.30). CSM was higher in ages 40-59 with stage III iCCA (HR = 2.60) and stage IV (HR = 2.81), as well as in 60-79 with stage III (HR = 2.24) and stage IV tumors (HR = 2.93). OM and CSM were higher in all age groups > 40 compared to the younger population. Conclusions: In this large retrospective study using the SEER database, we unfolded an aspect of iCCA mortality that has not been previously studied. We found a significant interaction between two independent prognostic factors that enhance mortality. This data may assist treating oncologists in selecting patients that would benefit from early aggressive treatment modalities which proved to be beneficial as seen in our study. This study paves the way for future prospective randomized clinical trials to further understand the impact of such interactions in patients with iCCA, especially in the era of precision oncology.