S1254
Clinical - Urology
ESTRO 2026
Material/Methods: Biomedical databases (PubMed, Embase, and CENTRAL) were searched for randomised controlled trials (RCTs) comparing adjuvant radiotherapy with observation. The revised Cochrane Risk of Bias (ROB 2.0) tool was employed to assess the risk of bias for individual trials. The outcomes of interests included locoregional recurrence-free survival (LRFS), disease- free survival (DFS), distant metastasis-free survival (DMFS), overall survival (OS), and adverse events. For the efficacy outcomes, hazard ratios (HRs) from individual trials were pooled using random-effects meta-analysis model. Adverse events were summarised using odd ratios (ORs). Statistical heterogeneity was assessed with the I2 statistic. Subgroup analysis was performed based on nodal status and receipt of neoadjuvant chemotherapy. This study followed the PRISMA guideline and was registered with PROSPERO (CRD420251230173). Results: Five RCTs comprising 747 patients were identified. Two older trials (1986, 1992) were judged as having high risk of bias, while three modern trials had low risk and predominantly enrolled patients with urothelial histology and negative surgical margins. Compared with observation, adjuvant radiotherapy significantly improved LRFS (HR, 0.29; 95% confidence interval (CI), 0.13-0.67; P = 0.0037; I2 = 51%), DFS (HR, 0.59; 95% CI, 0.41-0.84; P = 0.0031; I2 = 0%), and OS (HR, 0.73; 95% CI, 0.53-0.99; P = 0.04; I2 = 0%). Adjuvant radiotherapy did not result in significantly improved DMFS (HR, 0.73; 95% CI, 0.42-1.28; P = 0.27; I2 = 0%). The benefit of locoregional control was consistently observed across subgroups, including node-positive or node-negative disease (interaction P = 0.63) and those with or without neoadjuvant chemotherapy (interaction P = 0.85). With conformal techniques, adjuvant radiotherapy was not associated with a significant increase in late grade 3 or greater gastrointestinal (OR, 2.87; P = 0.15) or genitourinary toxicity (OR, 0.57; P = 0.78). Conclusion: Adjuvant radiotherapy significantly improves locoregional control, disease-free survival, and overall survival after radical cystectomy for muscle-invasive bladder cancer, without increasing severe late gastrointestinal or genitourinary toxicity when modern conformal techniques are used. Adjuvant radiotherapy should be considered for select high-risk patients. Further research is warranted to define its role in the era of immunotherapy. References: 1. Zaghloul et al. Radiotherapy Oncology. 19862. Zaghloul et al. International Journal of Radiation Oncology, Biology, Physics. 19923. Zaghloul et al. JAMA Surgery. 20184. Zaghloul et al. International Journal of Radiation Oncology, Biology, Physics. 20245. Murthy et
Conclusion: Prostate SBRT with a focal DIL boost up to 45 Gy is associated with favorable early safety and efficacy results. The use of rectal spacer significantly improves dosimetric parameters, with a corresponding non- significant reduction in rectal side effects. Keywords: SBRT, prostate cancer, rectal spacing Mini-Oral 3185 Adjuvant radiotherapy following radical cystectomy in muscle-invasive bladder cancer: a systematic review and meta-analysis of randomised trials Chia Ching Lee 1 , Wiwatchai Sittiwong 2 1 Radiation Oncology, National University Cancer Institute Singapore, Singapore, Singapore. 2 Radiology (Division of Radiation Oncology), Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand Purpose/Objective: This study aims to evaluate the efficacy and safety of adjuvant radiotherapy compared with observation following radical cystectomy in patients with non- metastatic muscle-invasive bladder cancer.
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