Does transurethral resection of prostate increase toxicity risk after simultaneous integrated boost radiotherapy?...

To evaluate genitourinary (GU) toxicity in patients with prostate cancer receiving conventional radiotherapy (RT) with a simultaneous integrated boost (SIB) to intraprostatic lesions (IPL), with a specific focus on those with a history of transurethral resection of the prostate (TURP).

This retrospective study initially included 606 patients with localized prostate cancer treated with definitive image-guided external beam RT between 2012 and 2023. Of these, 79 patients (13%) had a history of TURP. To reduce potential bias and balance baseline characteristics, 1:1 propensity score matching (PSM) was performed based on age, cardiac disease, diabetes mellitus, RT field, and androgen deprivation therapy (ADT) use. After matching, 158 patients (79 TURP vs. 79 no-TURP) were included in the final analysis. SIB was delivered to IPLs up to 86 Gy in 39 fractions. Toxicities were recorded according to CTCAE v4.03, and logistic regression was used to identify predictors of late GU toxicity.

In the matched cohort, baseline urinary function, α‑blocker use, prostate and IPL volumes, and IPL localisation were well balanced between groups. After a median follow-up of 78 months, late Grade ≥ 2 GU toxicity occurred in 21.5% of TURP vs. 7.6% of non-TURP patients (p = 0.02). The median time to late toxicity was significantly shorter among TURP patients (16 vs. 47 months, p = 0.007). On multivariable analysis, prior TURP and diabetes mellitus were independently associated with increased risk of late grade ≥ 2 GU toxicity.

Prior TURP is independently associated with higher and earlier-onset late GU toxicity in patients with prostate cancer receiving modern SIB-based RT. These results suggest that TURP status should be incorporated into personalized RT planning.