S1287
Clinical - Urology
ESTRO 2026
treated with moderate hypofractionation. Material/Methods:
seminal vesicle (81%). PTV margins ranged from 3- 5mm, with an anisotropic 5mm margin with 3mm posteriorly being the most common (56%). 19 (45%) ROs offer focal boost to the intra-prostatic lesion, contoured based on combination of MRI and PSMA- PET. The most common dose fractionation was 36.25 Gy to PTV and 40 Gy to CTV over 5 fractions, delivered as 2 (50%) to 3 (76%) fractions per week, and intraprostatic lesion boost of up to 42-45 Gy. The majority ROs offer prostate SABR on standard CT-Linac (88%), with several ROs also treating patients on Cyberknife (10%) and MR-Linac (5%). Of the ROs who use standard CT-Linac, 84% use intrafraction motion monitoring.There were 12 (23%) ROs who are not offering prostate SABR. The main barriers cited were lack of expertise (42%) and limited access to necessary technologies—including intrafraction motion management (25%), fiducial markers (17%), and planning MRI (8%). Conclusion: This ANZ-wide prostate SABR pattern of practice survey demonstrates variation in practice, offering contemporary insights into prostate SABR delivery across ANZ and identifying barriers to wider adoption. This information will be used to guide the development of a bi-national prostate SABR guideline to facilitate a broader evidence-based adoption of prostate SABR in ANZ. Keywords: Prostate, SABR, Survey, Digital Poster Highlight 4009 Daily CBCT-based oART vs IGRT in localized prostate cancer: toxicity and quality of life in a prospective parallel-cohort study Goda Kalinauskaite 1,2 , Luise Anna Künzel 1 , Kerstin Rubarth 1,3 , Thao Nguyen 1,3 , Jakob Danneh 1 , Celina Mandy Höhne 1 , Marcus Beck 1 , Julia Bauer 1 , Daniel Zips 1 , Carolin Senger 1 1 Department of Radiation Oncology, Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and HumboldtUniversität zu Berlin, Berlin, Germany. 2 Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Berlin, Germany. 3 Institute of Biometry and Clinical Epidemiology, Charité – Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and HumboldtUniversität zu Berlin, Berlin, Germany Purpose/Objective: To prospectively compare clinician-reported acute toxicity and patient-reported non-cancer specific Health-related quality of life (HRQoL) between daily cone-beam CT (CBCT)-based online adaptive radiotherapy (oART) and image-guided radiotherapy (IGRT) in patients with localized prostate cancer
In this prospective single-center parallel-cohort study (NCT06116019), 74 patients with localized prostate cancer received either CBCT-based oART (n=43) or CBCT-based IGRT (n=31) with 62 Gy in 20 fractions. Acute gastrointestinal (GI) and genitourinary (GU) toxicity was assessed weekly using CTCAE v5.0. HRQoL was evaluated using the EORTC QLQ-C30 questionnaire at baseline and end of therapy. Between-group differences were tested using Wilcoxon rank-sum tests; temporal and between- group changes were evaluated based on minimally clinically important differences (MCID) (1). Results: Baseline patient and treatment characteristics were similar, except for more high-risk tumors in the oART group (40.5% vs. 9.7%, p = 0.03). oART was associated with a more favorable GI toxicity profile (Figure 1). Grade 0–1 GI toxicity occurred in 86% (oART) vs 51% (IGRT), while grade ≥ 2 events were less frequent with oART (14% vs 45%, p = 0.028). No grade 4 events were observed. GU toxicity was comparable between groups (grade ≥ 2: 40% with oART vs 36% with IGRT, p = 0.793). More IGRT patients exceeded MCID thresholds for fatigue (74% vs. 37%, p = 0.004), physical (27% vs. 3%, p = 0.009), and role functioning (48% vs. 23%, p = 0.04, Table 1). Differences for pain, social function, and diarrhea were not significant but consistently favored oART.
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