Stereotactic Body Radiation Therapy for Cholangiocarcinoma: Optimizing Locoregional Control With Elective Nodal Irradiation

PURPOSE: To review our institutional experience of treating cholangiocarcinoma using stereotactic body radiation therapy (SBRT). METHODS AND MATERIALS: A total of 40 patients with intrahepatic (n = 25) or perihilar (n = 15) cholangiocarcinoma treated with SBRT were retrospectively reviewed. SBRT was delivered in 1 to 5 fractions with median dose of 40 Gy. Competing risk analysis was used to estimate cumulative incidence of local in-field, local out-of-field, regional, and distant failure. Kaplan-Meier and log-rank tests were used to calculate overall survival (OS). Toxicity was scored using Common Terminology Criteria for Adverse Events, version 4.0. RESULTS: The median follow-up time was 18 months. The 1-year incidence of local in-field, local out-of-field, regional, and distant failure was 8%, 23%, 13%, and 22%, respectively. Median OS was 23 months and 1- and 2-year OS rates were 69% and 39%, respectively. Patients with perihilar tumors had a 1-year incidence of regional failure of 24% and worse OS (P = .013). Patients with regional failure were more likely to develop distant metastases, 32% versus 19% at 1 year (P = .11). Acute grade 3 + hepatobiliary toxicity developed in 15 patients (36%). CONCLUSIONS: In this series of cholangiocarcinoma patients treated with definitive SBRT, patterns of failure reveal that regional failures are not insignificant, particularly for perihilar tumors. Elective nodal irradiation of regional lymphatics should be considered when using SBRT. A prospective study of elective nodal irradiation in patients with perihilar tumors would further clarify whether this approach improves outcomes without increasing hepatobiliary toxicity.