Safety and efficacy of transurethral resection of the prostate before external beam radiotherapy in patients with prostate cancer and lower urinary tract symptoms.

PURPOSE: To describe the safety and efficacy of planned transurethral resection of the prostate (TURP) prior to external beam radiotherapy (EBRT) in patients with prostate cancer and lower urinary tract symptoms. MATERIALS AND METHODS: Patients who underwent TURP ≤9 months before EBRT between March 2015 and March 2025 were included in this multicentre retrospective cohort. Urinary adverse events (UAE) were graded using Common Terminology Criteria for Adverse Events version 6. Cumulative incidence of grade ≥2 and ≥3 UAE was estimated with the Aalen-Johansen method with dead as a competing event, and associations with UAE after EBRT were explored with multivariable Cox regression. International Prostate Symptom Scores (IPSS) were analysed with linear mixed effects models. RESULTS: A total of 200 patients were included. Median follow-up after EBRT was 30 months among patients without a grade ≥3 UAE. The cumulative incidence at 36 months after EBRT was 53% (95% CI 46 - 61) for grade ≥2 and 14% (95% CI 9.1 - 20) for grade ≥3 UAE. A longer TURP-EBRT interval was associated with grade ≥2 UAE (hazard ratio 1.18 per month, 95% CI 1.03 - 1.36), likely reflecting confounding by indication. A larger clinical target prostate volume was associated with a lower risk of grade ≥3 UAE (HR 0.95 per mL, 95% CI 0.92 - 0.99). The estimated mean IPSS decreased from 19.8 before to 11.1 after TURP and remained close to or below this level after EBRT. CONCLUSIONS: Pre-EBRT TURP is feasible, with manageable but clinically relevant urinary toxicity. Symptom improvement is maintained after EBRT. These findings support its use as a de-obstructive strategy in patients with prostate cancer and lower urinary tract symptoms requiring EBRT.