BackgroundTo evaluate the clinical efficacy of percutaneous biliary drainage (PBD) combined with125I seed strand brachytherapy (ISSB) for the treatment of hilar cholangiocarcinoma (HCCA).MethodsThe clinical data of 64 patients with HCCA (median age 62.5, male 29, female 35) treated in our department from April 2017 to April 2021 were retrospectively analyzed. Thirty-four patients in the experimental group (EG) were treated with PBD combined with ISSB, while 30 patients in the control group (CG) were treated with PBD alone. The primary study endpoints were technical success, clinical success and the 2-month local tumor control (LTC) rate. Secondary endpoints were early/late complications, median progression-free survival (mPFS) and overall survival (mOS).ResultsThe technical and clinical success in the EG and CG showed no significant differences (100 vs. 100%, 94.1 vs. 93.3%,P> 0.05). Both early and late complications showed no significant differences between the two groups (P> 0.05). The 2-month LTC rates were significantly better in the EG versus the CG (94.1% vs. 26.7%, 157.7 ± 115.3 vs. 478.1 ± 235.3 U/ml), respectively (P< 0.05). The mPFS and mOS were 4.3 (95% CI 3.9–4.7) months and 2.8 (95% CI 2.5–3.1) months and 13.5 (95% CI 10.7–16.3) months and 8.8 (95% CI 7.8–9.8) months, respectively, with significant differences (P< 0.05).ConclusionPBD combined with ISSB is a safe and effective treatment for HCCA that can inhibit local tumors and prolong PFS and OS.