S1179
Clinical - Urology
ESTRO 2026
The median follow-up duration was 29 months, providing substantial observational data for analysis. Both treatment groups demonstrated excellent comparability across all essential baseline characteristics including age distribution, T-stage classification, histological features, and ECOG performance status. The overall study population was predominantly male (85.1%) with a mean age of 71.5 years, reflecting typical MIBC epidemiological patterns. For the complete cohort, OS rates measured 87% and 74% at 12 and 24 months respectively, while LRFS reached 91% and 85%, and DMFS achieved 89% and 85% at corresponding intervals. Bivariate analysis identified significant renal impairment (p=0.048) and ECOG performance status 2 (p=0.027) as independent predictors of diminished OS. Multivariate modeling established advanced patient age and specific chemotherapy scheduling as significant determinants for inferior outcomes across all survival endpoints.Comparative assessment between radiotherapy regimens revealed significantly enhanced OS in the H-RT cohort (91% and 78% versus 83% and 71% at 12/24 months, respectively; p=0.014), while LRFS and DMFS demonstrated statistical equivalence between treatment groups. Comprehensive toxicity assessment showed H-RT associated with substantially reduced acute gastrointestinal (26.1% versus 70.8%, p=0.002) and genitourinary adverse events (43.5% versus 75%, p=0.028). Implementation of modern intensity- modulated radiotherapy techniques correlated with significantly diminished late gastrointestinal toxicity (5.9% versus 30.8%, p=0.022) Conclusion: Hypofractionated radiotherapy limited exclusively to the bladder demonstrated equivalent oncological control compared to standard pelvic irradiation, while exhibiting superior survival outcomes and significantly improved acute toxicity profiles. These robust real- world findings substantiate H-RT as an effective and better-tolerated standard therapeutic option within contemporary trimodality management of MIBC, supporting its routine clinical implementation in appropriate patient populations. References: 1-Rodel C, et al. J Clin Oncol. 2002;20:3061-71. https://doi.org/10.1200/JCO.2002.11.0272-Stenzl A, et al. Eur Urol. 2010:288- 93. https://doi.org/10.1016/j.eururo.2011.03.0233- Zlotta AR, et al. Lancet Oncol. 2023;24:669-81. https://doi.org/10.1016/S1470-2045(23)00170-54- Choudhury A, et al. Lancet Oncol.2021;22:246-55. https://doi.org/10.1016/S1470-2045(20)30607-05-Patel SA, et al. Urol Oncol. 2023;41:325.e15-23. https://doi.org/10.1016/j.urolonc.2022.12.011 Keywords: MIBC, Trimodality Therapy, hypofractionation
Conclusion: reSBRT represents an effective and well-tolerated therapeutic option in selected patients. The prognostic score developed from this study may serve as a decision-support tool to optimize the selection of candidates for re-irradiation and to tailor follow-up and therapeutic strategies. External prospective validation is warranted to confirm its robustness and value. Keywords: Prostate Re-irradiation Need for Pelvic Inclusion with Hypofractionated Regimens in Muscle-Invasive Bladder Cancer: An Institutional Experience with Real-World Patients Iara Agustina Rivas, Ariel Matias Gomez Palacios, Luciana Brun, Jose Agustin Gilardi, Ana Faime Raies Miranda, Belen Raiden, Ofelia Perez Conci, Diego Fernandez, Lucas Caussa, Maria Fernanda Diaz Vazquez, Gustavo Ferraris Radiotherapy, Centro de Radioterapia Dean Funes, Cordoba, Argentina Digital Poster Highlight 1269 Purpose/Objective: Muscle-invasive bladder cancer (MIBC) is an aggressive malignancy with five-year survival below 50%1. Trimodality therapy (TMT)—combining TURBT, radiotherapy (RT), and chemotherapy—has emerged as an effective bladder-preserving alternative to radical cystectomy2-3. The benefit of elective pelvic nodal irradiation (PNI) remains uncertain with hypofractionated regimens4-5. This study compares outcomes between standard fractionation RT with PNI (S-RT) and hypofractionated RT to bladder alone (H-RT) in non-metastatic MIBC. Material/Methods: We conducted a retrospective study at Centro de Radioterapia Deán Funes (2017-2023), including 47 MIBC patients (T2-T3abN0M0) staged by CT. All underwent organ preservation via maximal TURBT followed by RT with chemotherapy (concurrent, neoadyuvante, or both). Patients were divided into S- RT (64Gy/32 fractions with PNI) and H-RT (55Gy/20 fractions to bladder alone). We evaluated Overall Survival (OS), Local Recurrence-Free Survival (LRFS), Distant Metastasis-Free Survival (DMFS), and toxicities (RTOG). Results:
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