Baseline Post-Void Residual Urinary Volume Is Associated with Acute Genitourinary Toxicity After Five-Fraction Stereotactic Body Radiation Therapy for Localized Prostate Cancer

Background/Objectives: We investigated the association between baseline post-void residual urine volume (PVR) and acute genitourinary (GU) toxicity after prostate stereotactic body radiation therapy (SBRT).

Methods

We retrospectively analyzed 140 consecutive patients treated with 36.25 Gy in five every-other-day fractions. The primary endpoint was the maximum clinically assessed acute Grade 2 GU toxicity during treatment or within 90 days after SBRT.

Results

Grade 2 toxicity occurred in 26/140 patients (18.6%). For PVR ≥ 40 mL, Grade 2 toxicity occurred in 12/34 (35.3%) versus 14/106 (13.2%) patients (unadjusted OR 3.58, 95% CI 1.46–8.82). After adjustment for age and baseline IPSS, the OR was 3.464 (95% CI 1.389–8.637; p = 0.0077). Apparent discrimination of the adjusted model was modest (AUC 0.670 (95% CI 0.539–0.801)).