S1136
Clinical - Urology
ESTRO 2026
Deviation (cc)PTV88.3743.56Bladder183.86149.99Rectum5.2617. 15The bladder and rectal dose on the approved plan were 967.05 cGy + 529.42 cGy and 173.94 cGy + 75.93 cGy respectively. The median + SD difference in dose received by the bladder and rectum from planning to delivery was 49.68 cGy + 276.26 cGy and 46.86 cGy + 213.88 cGy respectively. The median follow-up was 22.4 months (range 14-45 months). 1 patient developed grade 3 acute bladder toxicity that resolved within 30 days with symptomatic medications. No other patients developed any acute or late bladder or rectal toxicity. No correlation was found between the dosimetric differences and toxicities ( ρ ~0, p<0.0001)
Symptoms: The NRG-GU003 Phase 3 Randomized Clinical Trial. JAMA Oncol. 2024 May 1;10(5):584– 91.2. Vale CL, Fisher D, Kneebone A, Parker C, Pearse M, Richaud P, et al. Adjuvant or early salvage radiotherapy for the treatment of localised and locally advanced prostate cancer: a prospectively planned systematic review and meta-analysis of aggregate data. The Lancet. 2020 Oct 31;396(10260):1422–31. Keywords: Hypofractionation, salvage, prostate Dosimetric Differences From Planning To Delivery And Its Implications In Bladder And Rectal Toxicity In SBRT For Risk Prostate Cancer Vrushab Rao, Bhooshan Zade, Soumya Singh, Raghavendra Holla CyberKnife Radiosurgery and Radiation Oncology, Ruby Hall Clinic, Pune, India Purpose/Objective: Stereotactic body radiotherapy (SBRT) delivers high- doses of radiation with precision in fewer fractions and is a viable alternative to conventional radiotherapy for low and low-intermediate risk Digital Poster 373 prostate adenocarcinomas. Actual dose distributions may differ organ motion and variations in bladder and rectal filling. These organs-at-risk (OARs) may be more susceptible to toxicity as a result of these differences. This study aims to analyze the differences in the dose to the Planning Target Volume (PTV), bladder and rectum from planning to delivery in SBRT prostate, and identify any correlation due to this difference to any bladder or rectum side effects. Material/Methods: Patients with low and favourable-intermediate risk prostate cancers treated with 5-fraction SBRT prostate were included. All patients were simulated and treated with strict bladder filling and rectal emptying protocols. Planning was done using volumetric modulated arc therapy (VMAT) and baseline volumes and doses were recorded. Cone-beam CT (CBCT) scans were taken at each fraction. Precise matching of the PTV was done at each fraction. Post treatment delivery, the CBCTs were registered with the simulation scan and the bladder and rectum for each fraction were contoured. The plans for each fraction were recalculated and the dosimetry with its changes from the approved plan were recorded. Patients were followed-up for acute and late toxicities. Results: 30 patients were analysed as a part of this study. The median PTV volume, and median and standard deviation (SD) bladder and rectum volumes at simulation are stated in the table below. StructureMedian Volume (cc)Standard
Figure 1 - Comparison of dose received by the bladder.
Figure 2 - Comparison of dose received by the rectum. Conclusion: The variation in bladder and rectal volumes and doses does not correlate to toxicities of the organs when treated with strict preparation protocols and with optimal planning. Keywords: Prostate cancer, bladder and rectal toxicity Digital Poster Highlight 386 Integrating PSMA Radioligand Therapy with Pelvic Radiotherapy for Men with PSMA detected Oligorecurrent Pelvic Nodal Metastases of Prostate Cancer TEE SIN LIM 1,2 , Joe Cardaci 1,3 , Kirtenaa Prem Kumar 4 , Eugene Leong 5 , Vicki Sproule 6 , Nat Lenzo 7 1 Murdoch Oncology Centre (SJOG Murdoch), GenesisCare, Murdoch, Australia. 2 Department of Surgery, University of Western Australia, Nedlands,
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