S1189
Clinical - Urology
ESTRO 2026
Keywords: SBRT, High-risk prostate cancer, Late toxicity
for SBRT and 13.1% for IMRT (p = 0.583), while late grade ≥ 2 genitourinary (GU) toxicity was 11.7% for SBRT versus 16.4% for IMRT (p = 0.455), indicating no significant difference. However, considering all persistent GU adverse events (grade ≥ 1), IMRT showed a significantly higher incidence compared to SBRT (98.4% vs 78.3%, p = 0.0004). Bowel function (EPIC domain) declined modestly from 6 to 12 months post-SBRT but remained within good-function ranges. Notably, SBRT was associated with lower (worse) EPIC bowel scores at 9 months (p = 0.022 absolute; p = 0.0017 change from baseline) and 12 months (p = 0.018 absolute; p = 0.012 change from baseline) compared to IMRT, reflecting a consistent but modest QoL difference. Urinary, sexual, and hormonal EPIC domains, as well as IPSS scores, were comparable and stable between groups.
Poster Discussion 1690 Impact of Medical Operability For Primary Renal Cell Carcinoma After Stereotactic Ablative Radiotherapy Vivian S Tan 1 , Muhammad Ali 1,2 , Mathias Bressel 2,3 , Mark Shaw 1 , David Chang 1,2 , Sarat Chander 1,2 , Lewis Au 2,4 , Lavinia Spain 2,4 , Nathan Lawrentschuk 2,5 , Sree Appu 6 , Jamie Kearsley 7 , Weranja Ranasinghe 8,9 , Jeremy Goad 10 , Declan G Murphy 10 , Renu Eapen 10 , Marlon Perera 10 , Daniel Moon 10 , Shankar Siva 1,2 1 Department of Radiation Oncology, Peter McCallum Cancer Centre, Melbourne, Australia. 2 Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia. 3 Centre for Biostatistics and Clinical Trials, Peter McCallum Cancer Centre, Melbourne, Australia. 4 Department of Medical Oncology, Peter McCallum Cancer Centre, Melbourne, Australia. 5 Department of Surgery, University of Melbourne, Melbourne, Australia. 6 Department of Urology, Cabrini Clinical School, Melbourne, Australia. 7 Department of Urology, Royal Melbourne Hospital, Melbourne, Australia. 8 Department of Urology, Monash Health, Melbourne, Australia. 9 Department of Surgery, Monash Health, Melbourne, Australia. 10 Division of Cancer Surgery, Peter McCallum Cancer Centre, Melbourne, Australia Purpose/Objective: SABR is largely utilized to treat renal tumours in patients medically unfit for surgery (medically inoperable)[1]. However, some patients fit for surgery (medically operable) may undergo SABR. The objective of this study was to evaluate clinical outcomes between medically inoperable and operable localized RCC patients treated with SABR in a real-world setting. Material/Methods: All adult patients who underwent SABR for biopsy- proven or radiologically suspected localized RCC between January 2012 and December 2024 at a single- institution were reviewed retrospectively. Medical inoperability was determined a priori during multidisciplinary rounds. Patients were treated either with 26Gy in 1 fraction or 42Gy in 3 fractions. Clinical outcomes assessed included overall survival (OS), local control (LC), freedom from progression (FFP) and cancer-specific survival (CSS). OS was compared between inoperable and operable patients using restricted mean survival time (RMST) due to non- proportional hazard using 60 months as cutoff. Results: A total of 192 patients were included (inoperable n=104, operable n=88) who were followed for a
Conclusion: At one-year post-treatment, pelvis-inclusive, once- weekly SBRT demonstrated sustained tolerability and stable QoL relative to IMRT. While the acute GI advantage of SBRT was not reflected in late bowel QoL scores, the difference remained modest and within clinically acceptable ranges. The trial provides foundational data supporting the safety and feasibility of pelvis-inclusive 5-fraction SBRT in high-risk prostate cancer, informing ongoing phase III investigations. References: 1. Murthy V et al. Prostate-Only Versus Whole-Pelvic Radiation Therapy in High-Risk and Very High-Risk Prostate Cancer (POP-RT): Outcomes From Phase Ill Randomized Controlled Trial. J Clin Oncol 2021;39(11):1234-12422. Houlihan OA et al. A Randomized Feasibility Trial of Stereotactic Prostate Radiation Therapy With or Without Elective Nodal Irradiation in High-Risk Localized Prostate Cancer (SPORT Trial). Int J Radiat Oncol Biol Phys. 2023;117(3) 594-609.3. Glicksman RM et al. Elective pelvic nodal irradiation in the setting of ultrahypofractionated versus moderately hypofractioned and conventionally fractionated radiotherapy for prostate cancer: Outcomes from 3 prospective clinical trials. Clin Transl Radial Oncol. 2024;49:10084
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