S1139
Clinical - Urology
ESTRO 2026
Digital Poster 435
Decreased skeletal muscle quantity is associated with inferior overall survival in bladder cancer patients treated with radiotherapy. Alexander J Vickers 1,2 , Dónal M McSweeney 1,2 , Ananya Choudhury 1,2 , Jamie Weaver 1,2 , Gareth Price 1,2 , Alan McWilliam 1,2 1 Radiotherapy Related Research, The Christie NHS Foundation Trust, Manchester, United Kingdom. 2 Faculty of Biology, Medicine & Health, University of Manchester, Manchester, United Kingdom Purpose/Objective: Decreased skeletal muscle (SM) quantity and quality (through increased intramuscular adipose tissue (IMAT)) are associated with inferior outcomes in multiple cancers [1, 2]. Previous studies of elderly, frail bladder cancer patients, treated with radiotherapy alone, found that patients with decreased SM did not demonstrate inferior survival[3, 4]. We investigated whether a more complete body composition assessment is associated with inferior overall survival (OS). Material/Methods: Clinical and demographic data for 650 bladder cancer patients diagnosed between 2014-2022 and treated curatively with radiotherapy-based treatment at a single centre were available. An in-house AI tool segmented the SM at the L5 vertebra on radiotherapy planning scans. IMAT was calculated by thresholding the fat within the SM compartment. Segmentations were manually checked and failures excluded. Cross sectional SM area was corrected by height squared to give SM index (SMI). IMAT ratio (IMATR) was calculated
) was not associated with OS. Conclusion: This is the first study to show that muscle characteristics may be prognostic in bladder cancer patients treated curatively with radiotherapy. Streamlined body composition analysis in oncology workflows may allow stratification of patients at high risk of poor outcomes, impacting treatment decisions. Future work will assess a matched surgical cohort, investigating whether body composition is predictive or prognostic for OS in bladder cancer. References: 1. Shachar SS et al. Prognostic value of sarcopenia in adults with solid tumours: A meta- analysis and systematic review. Eur J Cancer. 2016;57:58-67.2. Aleixo GFP et al. Myosteatosis and prognosis in cancer: Systematic review and meta- analysis. Critical Reviews in Oncology/Hematology. 2020;145:102839.3. Stangl-Kremser J et al. Prognostic value of nutritional indices and body composition parameters including sarcopenia in patients treated with radiotherapy for urothelial carcinoma of the bladder. Urol Oncol. 2019;37(6):372- 9.4. Ferini G et al. Curative Radiotherapy in Elderly Patients With Muscle Invasive Bladder Cancer: The Prognostic Role of Sarcopenia. In Vivo. 2021;35(1):571-8. Keywords: Body composition, Sarcopenia, Myosteatosis Post-treatment ADC predicts long-term outcomes after definitive radiotherapy for prostate cancer with or without focal boost Cem Onal 1,2 , Gurcan Erbay 3 , Ozan Cem Guler 1 , Aysenur Elmali 2 , Birhan Demirhan 4 , Philip Sutera 5 , Matthew P Deek 6 , Melek Yavuz 2 , Phuoc T Tran 7 1 Department of Radiation Oncology, Baskent University, Adana Dr. Turgut Noyan Research and Treatment Center, Adana, Turkey. 2 Department of Radiation Oncology, Baskent University Faculty of Medicine, Ankara, Turkey. 3 Department of Radiology, Baskent University, Adana Dr. Turgut Noyan Research and Treatment Center, Adana, Turkey. 4 Department of Radiation Oncology, Iskenderun Gelisim Hospital, Poster Discussion 468
by dividing IMAT area by the total muscle compartment area. Cox proportional hazard
regression assessed the association between body composition and OS, considering defined confounding variables: e.g. age, sex and disease stage. Results:
513 patients had scans available, 455 segmentations passed quality control. 391 of these patients had height recorded for normalisation. Higher SMI was the only variable associated with superior OS (hazard ratio (HR) 1.82, p=0.008). IMATR (HR 0.84, p=0.445
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