ESTRO 2025 - Abstract Book

S2122

Clinical - Urology

ESTRO 2025

Material/Methods: We included men aged ≥70 years with localised prostate cancer in the Victorian statewide Prostate Cancer Outcome Registry (PCOR-Vic) between 2008 and 2022. The primary outcomes were initial management (active treatment with surgery/ radiotherapy within 12 months vs observation) and survival outcomes. Multivariable logistic regressions were used to identify factors associated with active treatment, and multivariable Cox regressions and Fine-Gray models were used to evaluate factors associated with overall survival (OS) and prostate cancer specific mortality (PCSM), adjusting for covariables of interest. Results: There were 10,517 men included in the study, 9,063 (86%) aged 70- 79 years, and 1434 (14%) aged ≥80 years. There were 1,471 (14%), 5,374 (51%) and 3,672 (35%) with low-risk (LRPC), intermediate-risk (IRPC) and high-risk (HRPC) disease respectively. 7,249 (69%) men received active treatment – 6,613 (73%) in men aged 70-79 years, and 636 (44%) in men aged ≥80 years. The use of active treatment increased over time, from 63% in 2008 -2010 to 71% in 2020-2022 (P-trend<0.001). In multivariable analyses, increasing age, being diagnosed in public institutions and earlier year of diagnosis were independently associated with reduced likelihood of active treatment. The median follow-up for the cohort was 5.7 years (IQR: 3.6-8.4 years). There were 2,172 (21%) men who died, of which 361 (3%) were PCSM. For men with IRPC with active treatment vs observation, 5-year OS were 94% (95%CI=93-95%) and 87% (95%CI=85-89%) (P<0.001), and 5-year PCSM were 0.5% (95%CI=0.3-0.9%) and 1.0% (95%CI=0.5-1.8%) (P=0.2), respectively. For men with HRPC with active treatment vs observation, 5-year OS were 88% (95%CI=87-89%) and 63% (95%CI=59-67%) (P<0.001), and 5-year PCSM were 4.1% (95%CI=3.4-5.0%) and 10.8% (95%CI=8.2-14.3%) (P<0.001), respectively. In multivariable analyses, active treatment was associated with OS benefits for IRPC (HR=0.70;95%CI=0.61-0.82;P<0.001) and HRPC (HR=0.61;95%CI=0.52-0.7;P<0.001), but no differences in PCSM for both IRPC (sHR=1.26;95%CI=0.75-2.11;P=0.4) and HRPC (sHR=0.85;95%CI=0.60-1.19;P=0.3). Conclusion: This is the largest Australian population-based analysis of prostate cancer management in older men, with increasing use of active treatment over time. Active treatment in older patients was associated with OS benefit, likely reflecting patient selection for treatment, but did not result in improvement in PCSM. This highlights the importance of patient selection when considering active treatment in older men with prostate cancer. Digital Poster Toxicity and tolerability of MR guided online adaptive radiotherapy (36Gy/6Fx) for bladder cancer in ederly patients Pia Braagaard Hartfelt 1 , Pia Krause Møller 1,2 , Rasmus Lübeck Christiansen 3 , Anders Smedegaard Bertelsen 3 , Tine Schytte 1,2 , Lars Dysager 1 1 Department of Oncology, Odense University Hospital, Odense, Denmark. 2 Department of Clinical Research, University of Southern Denmark, Odense, Denmark. 3 Laboratory of Radiation Physics, Odense University Hospital, Odense, Denmark Purpose/Objective: To evaluate the toxicity, effect, and overall survival (OS) in elderly patients with bladder cancer treated with adaptive radiation therapy, 36 Gy/6 fractions, on an MR-Linac. Material/Methods: A descriptive study of frail patients with bladder cancer treated with adaptive radiation therapy (36 Gy in 6 fractions) on a 1.5T MR-Linac, with one fraction delivered per week. Prior to treatment, the bladder tumor was either Keywords: prostate cancer, registry, elderly 4310