S1182
Clinical - Urology
ESTRO 2026
propensity treatment weighting (IPTW) to adjust for baseline differences between treatment groups. Survival was analysed with a Cox proportional hazards model and Restricted mean survival time (RMST)
Mini-Oral 1386 Long-term oncological outcomes of radical cystectomy versus bladder-preserving therapy in muscle invasive bladder cancer. Katharina Brück 1,2 , Annemarie Leliveld 3 , Martine Franckena 4 , Michiel S. van der Heijden 5 , Carin A. Uyl-de Groot 6,7 , Joost L. Boormans 8 , Lisa M.C. van Hoogstraten 9 , Richard P. Meijer 10 , J. Alfred Witjes 11 , A. Rogier Donders 12 , Lambertus A. Kiemeney 12 , Maarten C.C.M Hulshof 1,2 , Katja K.H. Aben 12,9 1 Radiation Oncology, Amsterdam UMC, Amsterdam, Netherlands. 2 Treatment and quality of life, Cancer Center Amsterdam, Amsterdam, Netherlands. 3 Urology, UMC Groningen, Groningen, Netherlands. 4 Radiation Oncology, Erasmus MC, Rotterdam, Netherlands. 5 Medical Oncology, Netherlans Cancer Institute, Amsterdam, Netherlands. 6 Health Technology Assessment, Institute for Medical Technology Assessment, Rotterdam, Netherlands. 7 Health Economics, Erasmus School of Health & Policy Management, Rotterdam, Netherlands. 8 Urology, Erasmus MC, Rotterdam, Netherlands. 9 Research & Development, Netherlands Comprehensive Cancer Organization, Utrecht, Netherlands. 10 Oncological Urology, University Medical Center Utrecht, Utrecht, Netherlands. 11 Urology, Radboud university medical center, Nijmegen, Netherlands. 12 IQ Health Science, Radboud university medical centre, Nijmegen, Netherlands Purpose/Objective: After a failed Randomized clinical trial (RCT) due to poor accrual, an RCT comparing radical cystectomy (RC) and bladder preserving therapy (BPT) in patients with muscle invasive bladder cancer (MIBC) is deemed unfeasible. A large observational study is an alternative to compare outcomes between these modalities.Objective:To compare the survival of patients with non-metastasized MIBC treated with BPT versus those treated with RC. Material/Methods: Design, Setting and Participants:All patients diagnosed with non-metastatic MIBC (with predominantly urothelial carcinoma histology) between November 2017 and November 2019 in the Netherlands were identified via the population-based Netherlands Cancer Registry. Only patients treated with curative intent using either BPT or RC were included. BPT was defined as treatment with concurrent chemoradiation or external beam radiotherapy followed by a brachytherapy boost.Outcome Measurements and Statistical Analysis:The primary endpoint was the 5- year disease-free survival (DFS), defined as the time from treatment start until loco-regional recurrence, distant metastasis or death. The secondary endpoint was the overall survival (OS). We used inverse
analysis. Results:
A total of 1431 patients were included, of whom 1100 underwent RC and 331 BPT. Median follow-up was 63 months (range: 51-75 months). Figure 1 shows the IPTW DFS. The 5-year weighted DFS in the RC and BPT group was 46.4% (95%CI 43.1-49.7%) and 43.8% (95%CI 35.3-52.3%), respectively. Patients treated by RC and BPT had similar DFS with an adjusted HR 0.95 (95%CI 0.80-1.12). The RMST difference was 1.8 months (p=.2431) at 5 years.Figure 2 shows the IPTW OS. The 5-year weighted OS for patients treated with RC versus BPT was 52.9% (95%CI 49.7-56.1%) versus 52.7% (95%CI 44.9-60.6%) with an adjusted HR of 0.95 (95%CI 0.80-1.13). The RMST difference was 2.9 months (p=.0341) at 5 years.Figure 1. Weighted disease-free survival of patients with non- metastatic muscle invasive bladder cancer treated with either radical cystectomy or bladder-sparing treatment, including 95%CI and numbers at risk.
Figure 2 Weighted overall survival of patients with non- metastatic muscle invasive bladder cancer treated with either radical cystectomy or bladder- sparing treatment, including 95%CI and numbers at risk.
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