Objective To observe the prognosis of prostate cancer patients with pubic arch interference (PAI) during ¹²⁵I brachytherapy and analyze the influencing factors of biochemical recurrence-free survival (bRFS) and overall survival (OS).

Methods A retrospective analysis was conducted on the clinical data of 141 prostate cancer patients with PAI who underwent ¹²⁵I seed implantation brachytherapy at Northern Jiangsu People's Hospital Affiliated to Yangzhou University from July 2013 to December 2020. Perioperative data and prognostic information of patients were collected. LASSO regression analysis was used to screen key variables as predictors of bRFS and OS. The log-rank method was employed for univariate analysis of relevant indicators, and the Cox proportional hazards model was used for multivariate analysis to identify factors associated with bRFS and OS. The Kaplan-Meier curve was utilized for clinical efficacy.

Results The actual number of implanted needles was an independent predictor of bRFS, and the maximum pubic arch interference angle (AoPAImax) was an independent predictor of OS. Prostate volume and T staging were independent predictors of bRFS, and age was an independent predictor of OS (P < 0.05).

Conclusion For patients with PAI and a large prostate volume, brachytherapy and androgen deprivation therapy (ADT) can achieve a favorable prognosis. Patients with T3 prostate cancer should consider low-dose-rate brachytherapy (LDR-BT) combined with external beam radiation therapy and ADT. Patients with an actual number of implanted needles ≥ 27 have a better prognosis. LDR-BT should also be considered as a personalized definitive treatment option for patients aged < 75 years with an AoPAImax < 20°.