Ultra- and Moderately Hypofractionated Radiotherapy for Inoperable Cholangiocarcinoma: A Single-Institution Retrospective Analysis.

Systemic therapy is the mainstay of treatment in inoperable cholangiocarcinoma (CCA). The aim of this study was to evaluate the overall survival (OS), progression-free survival (PFS), recurrence patterns, and the association between biliary complications and OS in patients with inoperable, localized cholangiocarcinoma treated with radiotherapy (RT) alone. Records of patients treated between 2004 and 2022 who received a minimum of 32.5 Gy BED10 were retrospectively reviewed. Survival was estimated using the Kaplan-Meier method, and prognostic factors were assessed using univariate and multivariable analyses. A total of 56 patients (median age 67.5) were included, most of whom had intrahepatic (78.6%) CCA, and most of whom received SBRT (76.8%). The median dose was 36 Gy (BED 55 Gy), and the median OS and PFS were 20 months and 10 months, respectively. One-year local control was 92.1% and the primary site of progression was intrahepatic (64.9%). On univariate analyses, pre-radiation biliary obstruction, elevated baseline CA 19-9, larger tumor size, and age were associated with worse outcomes; on multivariable analysis, only lesion size was prognostic. Biliary complications were associated with inferior OS. These findings highlight the high intrahepatic out-of-field failure rates and suggest the incorporation of biliary-event-free survival as a clinically relevant endpoint.