Long-term efficacy and safety of helical tomotherapy for cholangiocarcinoma: A 10-year single-centre retrospective cohort study.

INTRODUCTION: Cholangiocarcinoma (CCA) is a heterogeneous biliary malignancy with a poor prognosis, and no standard radiotherapy regimen has been established. We evaluated long-term survival, toxicity, and prognostic factors in patients with CCA treated with helical tomotherapy (HT) at a single centre over 10 years. METHODS: Sixty-seven patients with CCA who received HT were retrospectively analysed. Disease was staged using the AJCC 8th edition. Overall survival (OS) was estimated by Kaplan-Meier analysis and compared using the log-rank test; Cox proportional hazards models identified prognostic factors. Toxicity was graded by CTCAE v5.0. RESULTS: Patients (58.2% male; mean age 61.4 ± 11.9 years) had iCCA (40.3%), hCCA (32.8%), or eCCA (26.9%); 61.2% had stage IV disease. Median follow-up was 13.0 months. Median OS was 14.0 months, with 1-, 2-, 3-, and 5-year OS rates of 55.0%, 30.5%, 19.8%, and 14.4%. Poor differentiation independently predicted worse OS (HR = 5.49; 95% CI, 1.48-20.41; p = 0.011). No grade ≥3 gastrointestinal toxicity occurred; one patient (1.5%) had grade 3 haematologic toxicity. CONCLUSION: In this heterogeneous cohort treated with HT, median OS was 14.0 months with no severe gastrointestinal toxicity. Poor histological differentiation was associated with worse OS. Given heterogeneity in treatment intent, stage, and systemic therapy, findings should be interpreted cautiously. IMPLICATIONS FOR PRACTICE: In this retrospective cohort, HT was well tolerated in the acute setting, with no severe gastrointestinal toxicity recorded, supporting its feasibility in this anatomically challenging disease. Histological differentiation may inform prognostic counselling and patient selection but requires prospective validation. Prospective studies of dose-escalated HT are needed to define its role in multimodal management.