ESTRO 2025 - Abstract Book

S400

Brachytherapy - Urology

ESTRO 2025

2.Lavan NA et al. The curative management of synchronous rectal and prostate cancer. Br J Radiol. 2016;89(1057):20150292. 3.Chiang JS et al, Radiotherapeutic Management of Synchronous Prostate and Rectal Cancers Using Proton Beam Therapy. Int J Part Ther. 2021 Apr 20;8(2):82-88. 4.Owens, Robert et al.Treatment of synchronous rectal and prostate cancer utilising intensity-modulated radiotherapy (IMRT) with a simultaneous integrated boost (SIB): Assessment of acute toxicity and response. Annals of Oncology, Volume 28, iii132 - iii133

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Digital Poster The association between dose and location of the dominant intraprostatic lesion with outcomes in patients treated with LDR prostate brachytherapy Orla A Houlihan 1,2 , Sergio Esteve 3 , Geraldine Workman 3 , Monica Byrne 3 , Eoin Napier 4 , Kevin M Prise 1 , Alan Hounsell 3 , Darren M Mitchell 2 , Suneil Jain 1,2 1 Patrick G. Johnston Centre for Cancer Research, Queen's University Belfast, Belfast, United Kingdom. 2 Clinical Oncology, Northern Ireland Cancer Centre, Belfast, United Kingdom. 3 Medical Physics, Northern Ireland Cancer Centre, Belfast, United Kingdom. 4 Radiology, Northern Ireland Cancer Centre, Belfast, United Kingdom Purpose/Objective: To investigate for an association between the dose received by the prostate sector in which the dominant intraprostatic lesion (DIL) was located and freedom from biochemical/clinical failure (BCF) among patients treated with low dose rate (LDR) prostate brachytherapy. Material/Methods: Prostate sector analysis was performed for 606 patients treated with LDR brachytherapy (145Gy monotherapy n=546; 110Gy combination n=60) at a single institution from 2009-20 (13% NCCN low, 80% intermediate, 7% high risk). Review of the diagnostic MRI (n=599) and pathology report (n=606) was performed to identify the prostate sector(s) containing the DIL. Outcomes were blinded during this process. The prostate was divided into 12 sectors; 3 equal thirds (base/midgland/apex), and 4 axial sectors by two separate methods; plus (“+”) and cross shape (“x”). Kaplan-Meier curves were generated with the log-rank test performed to assess for differences in BCF rates.