S1313
Clinical - Urology
ESTRO 2026
Mini-Oral 4941 Nationwide analysis of lower GI toxicity after prostate radiotherapy: comparison of radiotherapy modalities using National Health Registry Irena Koniarova 1 , Miriam Slezakova 2 , Lukas Kotik 2 , Klara Benesova 3 1 Medical Exposures Department, National Radiation Protection Institute, Prague, Czech Republic. 2 Radiation Risks Division, National Radiation Protection Institute, Prague, Czech Republic. 3 Department of Data Analysis, Institute of Health Information and Statistics of the Czech Republic, Prague, Czech Republic Purpose/Objective: This study aimed to analyse data from the National Health Insurance Registry and to identify associations between lower GI tract procedures and the management of post-radiation toxicity after prostate radiotherapy. Material/Methods: More than 1.3 million radiotherapy procedures performed between 2010 and 2022 in 34,879 prostate cancer patients in different centres were analysed. A control group five times larger was also included in the analysis. Lower GI procedures were classified by severity and recurrence into three categories. For low- grade and severe complications, only occurrence was evaluated; for recurrent events requiring repeated endoscopic intervention, both occurrence and frequency were analysed.Statistical models considered age, follow-up, geographical location, fractionation, IGRT, radiotherapy technique (3D-CRT, IMRT/VMAT, SBRT, proton therapy, tomotherapy) and other covariates. For low-grade and severe events, a Cox proportional hazards model (Andersen et al) was used. For recurrent events, the generalised Cox proportional hazards model (Lin et al) was applied. The results were adjusted for multiple comparisons. Results: Curves for recurrent and severe complications for each technique and centre are shown in the figures.For low-grade complications, significant differences were observed between hospitals and treatment modalities (p = 0.0027 and p = 0.006, respectively). For severe procedures, no statistically significant differences were found between techniques or centres, although interpretation was limited by low statistical power owing to the small number of events. In the case of recurrent bleeding-related procedures, stereotactic body radiosurgery (SBRT) demonstrated a significantly lower frequency of post- radiotherapy interventions, being the only modality
Conclusion: This extended follow-up demonstrates continued biochemical recurrences beyond 5-year surveillance, with ongoing events up to 10 years post-treatment. Despite worse prognostic features in the 70 Gy cohort, outcomes were comparable between doses, supporting potential risk-adapted dose escalation. These findings emphasize the need for prolonged follow-up protocols extending well beyond conventional 5-year timeframes. References: Forman JD, Velasco J. (1998) Therapeutic radiation in patients with a rising post-prostatectomy PSA level. Oncology (Williston Park) 12(1):33–39.Garg MK, Tekyi- Mensah S, Bolton S, Velasco J, Pontes E, Wood DP Jr, Porter AT, Forman JD. (1998) Impact of postprostatectomy prostate-specific antigen nadir on outcomes following salvage radiotherapy. Urology 51(6):998–1002.Ghadjar P et al. Swiss Group for Clinical Cancer Research (SAKK). Dose-intensified Versus Conventional-dose Salvage Radiotherapy for Biochemically Recurrent Prostate Cancer After Prostatectomy: The SAKK 09/10 Randomized Phase 3 Trial. Eur Urol. 2021 Sep;80(3):306-31 Keywords: salvage radiotherapy
Made with FlippingBook - Share PDF online