Abstract No. 259 Selective Radioembolization for Early-Stage Intrahepatic Cholangiocarcinoma

There is increasing interest in the application of radiation segmentectomy (RS) with Yttrium-90 microspheres for treating liver cancers other than Hepatocellular Carcinoma. In this study, we aim to evaluate the efficacy of RS for the treatment of early-stage intrahepatic cholangiocarcinoma (ICC). With institutional review board approval, a retrospective chart review including all patients with T1a (solitary tumor ≤5 cm without vascular invasion) and T1b (solitary tumor >5 cm without vascular invasion) stage ICC according to The American Joint Committee on Cancer (AJCC) staging manual 8th edition, treated with RS (up to 2 Couinaud segments, > 190 Gray (Gy) based on MIRD dosimetry) from December 2007 to September 2019. Patient demographics, treatment details, time to local tumor progression (TTP), and overall survival (OS) were analyzed. Kaplan-Meier statistics were used to assess time to progression (TTP) and overall survival (OS) from date of RS and censored at last follow-up or date of resection. 15 patients with biopsy-confirmed disease met inclusion criteria (median age 65.5 years; 60% male); 11(73%) were classified as T1a and 4 (27%) as T1b. 13 patients were treatment naïve, while two received chemotherapy before RS. The median perfused volume was 201.4 cc (range 44.3-438.8), and received a median tumor absorbed dose of 308.2 Gy (range 194.2-879.3 Gy). Based on WHO criteria, best tumor response was complete response in 2 (13.3%), partial response in 7 (46.7%), and stable disease in 6 (40.0%) patients. The median censored target lesion TTP was 43.4 months (95% CI 26.0 to no estimate), and the median censored non-target liver TTP was not reached. The median censored OS was 71.8 months (95% CI 37.8-105.8), and 3 patients were resected (range 2.4-5.0 months after RS) for curative treatment, with pathology revealing complete pathologic necrosis. This study shows promising potential for RS in treating early-stage ICC. Prospective trials with larger sample sizes are required to confirm these findings and compare RS with other treatments for early-stage ICC.