Adjuvant Radiotherapy After Cystectomy in Muscle-Invasive Bladder Cancer: Indications, Benefits and Remaining Challenges.

Bladder cancer accounts for nearly 600,000 new cases and over 200,000 deaths annually worldwide. Approximately 25% of diagnoses correspond to muscle-invasive disease, and up to 50% of patients undergoing radical cystectomy experience recurrence within the first two years, with a 5-year overall survival reaching 50%-60%. Despite the use of neoadjuvant chemotherapy, clinical trials have failed to attain a considerable reduction in the risk of locoregional recurrence, which remains a major clinical challenge due to the limited and largely ineffective salvage treatment options. In this context, adjuvant radiotherapy (ART) has re-emerged as a potential strategy for reducing locoregional recurrence and improving metastasis-free survival, supported by advances in delivery techniques and a reassessment of safety concerns following the BART trial. Simultaneously, perioperative immunotherapy is reshaping the therapeutic landscape of muscle-invasive bladder cancer, with recent studies, such as CheckMate 274 and NIAGARA, establishing a new standard of care. The novelty of this review lies in the integration of the evolving role of ART within the immunotherapy era, with critical examination of its complementary value, toxicity profile and patient selection in light of modern systemic strategies. This narrative review provides an updated synthesis of current evidence and ongoing trials and offers a perspective on how ART can be optimally incorporated into multimodal management of high-risk bladder cancer.