ESTRO 2025 - Abstract Book

S1972

Clinical - Urology

ESTRO 2025

Urinary symptoms and incontinence were shown to negatively affect QOL in both group’s baseline questionnaires. However, there was a steady worsening of urinary symptoms reported over 60 months post RT, with an increase in the symptom scales from a mean of 15.9 at baseline to 22.9 at 60 months. There was a statistically significant difference in change of urinary symptoms between the treatment groups with the 70Gy arm reporting worse outcomes (21.74 vs. 24.21, p=0.012). Conclusion: Nearly half of the patients that were continent at baseline showed a decline during follow-up while incontinent patients showed a variable course. UI was not different between the RT treatment arms, however, 70Gy demonstrated a slight but statistically significant worsening of QOL related to the urinary symptom scale.

Keywords: urinary incontinence, prostate cancer, salvage

1808

Poster Discussion Phase II Study of MR-guided Prostate Stereotactic Body Radiotherapy in Seven Days: toxicity analysis – preliminary results Benjamin Vanspeybroeck, Jacques Bezuidenhout, Guy Soete, Jens Van Loon, Sven Van Laere, Tim Everaert, Anne Sophie Bom, Thierry Gevaert, Mark De Ridder Radiation Oncology, UZ Brussel, Brussels, Belgium Purpose/Objective: This study aims to evaluate acute genitourinary (GU) and gastro-intestinal (GI) toxicity after prostate cancer (Pca) stereotactic body radiotherapy (SBRT) delivering 36Gy in five fractions to the PTV and 40Gy to the CTV with a simultaneous integrated boost (SIB) to the intraprostatic tumor (GTV) up to 42Gy delivered by MR-guided radiotherapy (MRgRT) with 0,35-T MR Linac with an overall treatment time (OTT) of seven days. Material/Methods: This phase II Study, entitled Proseven, was approved by the Ethics committee of UZ Brussels (ClinicalTrials.gov NCT04896801). A sample size of 132 was determined, comprising 120 participants based on the actual sample size calculation and an additional 12 to account for an anticipated 10% dropout rate, to detect an increase of 10% in grade 2+ (grade 2 or higher) GU and GI toxicity. The primary endpoint was clinician reported grade 2+ acute GU and GI toxicity. Toxicity assessment was performed using CTCAE v5.0. Secondary endpoints are clinician reported acute and late toxicity, patient reported outcomes measures (PROM) and quality of life assessment , which are collected through patient-completed questionnaires (EPIC-26, IPSS, EORTC QLQ-C30, and QLQ-PR25) sent by mail, freedom from biochemical failure, disease-free and overall survival. Currently, the Proseven trial recruitment is finished, and follow-up (5 years) is still ongoing. The first patients are currently in follow-up for 36 months (i.e., 3 years). Results: A total of 132 patients with low (12.1%), intermediate (66.6%) and limited high risk (21.2%) prostate cancer were included in the analysis. The median initial PSA before RT was 9.43 ng/ml (range 2,8 – 27,6). A SIB to the GTV was executed in 82.6% of patients. 64.4% were treated with an OTT of seven days, 95.5% patients were treated with an OTT of 10 days or less. Grade 2 or more GU toxicity occurred in 35% at 12 weeks, and grade 2 or more GI toxicity occurred in 5% at 12 weeks (Figure 1). Acute Grade 3 GU occurred only in two cases. No acute Grade 3 GI toxicity was seen.