KEY POINTS
- This multi-institutional retrospective study evaluated 509 patients receiving definitive hypofractionated RT for localized prostate cancer; 494 were evaluable for toxicity, while baseline IPSS was available in a predefined analytic cohort of 156 patients.
- Patients received moderate hypofractionation over a median 20 fractions, ranging from 20–28 fractions with 2.5–3.0 Gy per fraction. Median follow-up was 42 months.
- Contemporary treatment was generally well tolerated. Acute grade ≥2 GU toxicity occurred in 22.5%, including 1.6% grade 3, while late grade ≥2 GU toxicity occurred in only 3.7%; late grade ≥2 GI toxicity was 4.0%.
- In the IPSS cohort, baseline urinary symptom burden was strongly associated with late GU toxicity. Each 1-point increase in IPSS increased the adjusted odds by 11% (adjusted OR 1.11, 95% CI 1.04–1.19; p=0.002).
- Bladder V30 and PTV volume were significant on univariable analysis but lost significance after adjustment: bladder V30 adjusted OR 1.02, p=0.412 and PTV volume adjusted OR 1.00, p=0.655. IPSS remained the only independent predictor.
- Importantly, the association persisted even among patients meeting accepted bladder dose-volume constraints, suggesting that a technically acceptable DVH does not fully capture an individual patient’s susceptibility to late urinary toxicity.
- The effect was consistent across age, bladder-dosimetry and fraction-size subgroups. However, only a small absolute number of late grade ≥2 GU events occurred, and toxicity was physician-graded rather than prospectively patient-reported, limiting precision.
CLINICAL TAKEAWAY
A baseline IPSS may add clinically useful information that bladder dosimetry alone cannot provide before hypofractionated prostate RT. A high score should not automatically exclude hypofractionation, but it may justify better symptom optimization, more careful counseling and closer urinary follow-up.