Abstract No. 4 ▪ ABSTRACT OF THE YEAR Twenty Years of Radiofrequency Ablation for Intrahepatic Cholangiocarcinoma: A Population Study

Intrahepatic cholangiocarcinoma (iCCA) is an insidious primary liver cancer traditionally treated by surgical resection and systemic therapy. Locoregional therapies such as thermoablation have introduced an alternative approach for unresectable iCCA. The present study aims to identify the trends in survival among iCCA patients undergoing thermoablation in a population database. Data retrieval was conducted using 17 registries from the Surveillance, Epidemiology, and End Results (SEER) database from 2000-2020. Overall survival (OS) was measured with Kaplan-Meier and Cox regression models. Subgroup analysis was performed based on race, sex, age, stage, tumor size, and time of iCCA diagnosis. For a total of 192 included patients, the mOS was 28 months (95%CI: 22-32 months) with 1, 3, and 5-year OS of 79.3%, 35.8%, and 19.8%, respectively. Patients diagnosed after 2010 demonstrated improved survival compared with those diagnosed before 2010 (mOS: 32 vs. 21 months, p=0.0020). Patients with local (3-yr-OS: 52%; 5-yr- OS:31.1%), regional (3-yr OS: 53%, 5-yr-OS:11.4%), or distant disease (3-yr-OS: 0%) demonstrated a mOS of 37 months, 40 months, and 13 months (p ≤ 0.0001), respectively. Tumor size of 3 cm or smaller (3yr OS: 55.1%; 5yr OS:41.2%) showed a mOS of 46 months; tumors measuring 3-5 cm (3yr OS: 39.7%; 5yr OS:9.1%) demonstrated a mOS of 32 months, whereas the mOS of patients with tumor >5 cm (3yr OS: 30.5%; 5yr OS:12.2%) was 23 months. Patients with iCCA undergoing thermoablation show improved outcomes if diagnosed after 2010. Additionally, patients with local disease and tumors 3 cm or smaller had superior survival outcomes.