Real‐World Efficacy of Postoperative Adjuvant Nivolumab in High‐Risk Urothelial Carcinoma: A Retrospective Comparative Study in an Asian Population

Purpose To evaluate the real‐world effectiveness of adjuvant nivolumab following radical surgery in patients with high‐risk urothelial carcinoma, using historical data for comparison. Materials and Methods Patients who underwent radical surgery at our institution were retrospectively analyzed. They were divided into two groups: one group received adjuvant nivolumab, and the other received no adjuvant therapy. Oncological outcomes, adverse events, and treatment completion rates were assessed. Results A total of 158 patients were included: 20 in the adjuvant nivolumab group and 138 in the control group. The median observation periods were 20.4 months in the nivolumab group and 36.7 months in the control group. The nivolumab group showed significantly improved recurrence‐free survival compared to the control group (hazard ratio: 0.21; 95% confidence interval: 0.10–0.42; p = 0.01). Although overall survival tended to improve in the nivolumab group, the difference was not statistically significant (hazard ratio: 0.32; 95% confidence interval: 0.01–1.01; p = 0.22). Multivariate analysis confirmed adjuvant nivolumab as a significant favorable prognostic factor for recurrence‐free survival (hazard ratio: 0.18; 95% confidence interval: 0.044–0.73; p = 0.017). One‐year treatment was completed in 55.0% of patients. Adverse events led to discontinuation in 25.0%, with major events including interstitial lung disease (three patients), hormonal disorders such as isolated adrenocorticotropic hormone deficiency (2), rash (3), hypothyroidism (1), and hepatitis (1). Conclusion Adjuvant nivolumab demonstrated clinical benefit in Asian patients with high‐risk urothelial carcinoma in a real‐world setting.