Carboplatin-based adjuvant chemotherapy versus observation after radical cystectomy in patients with pN1-3 urothelial bladder cancer

Purpose To test the impact of carboplatin-based ACT on overall survival (OS) in patients with pN1-3 cM0 BCa. Methods A retrospective analysis was conducted on 1057 patients with pTany pN1-3 cM0 urothelial BCa treated with or without carboplatin-based ACT after radical cystectomy and bilateral lymph-node dissection between 2002 and 2018 at 12 European and North-American hospitals. No patient received neoadjuvant chemotherapy or radiation therapy. Only patients with negative surgical margins at surgery were included. A 3:1 propensity score matching (PSM) was performed using logistic regression to adjust for baseline characteristics. Univariable and multivariable Cox regression analyses were used to predict the effect of carboplatin-based ACT on OS. The Kaplan-Meier method was used to display OS in the matched cohort. Results Of the 1057 patients included in the study, 69 (6.5%) received carboplatin-based ACT. After PSM, 244 total patients were identified in two cohorts that did not differ for baseline characteristics. Death was recorded in 114 (46.7%) patients over a median follow-up of 19 months. In the multivariable Cox regression analyses, increasing age at surgery (hazard ratio [HR] 1.02, 95% confidence interval [CI] 1.01-1.06, p < 0.001) and increasing number of positive lymph nodes (HR 1.06, 95% CI 1.01-1.07, p = 0.02) were independent predictors of worse OS. The delivery of carboplatin-based ACT was not predictive of improved OS (HR 0.67, 95% CI 0.43-1.04, p = 0.08). The main limitations of this study are its retrospective design and the relatively low number of patients involved. Conclusions Carboplatin-based might not improve OS in patients with pN1-3 cM0 BCa. Our results underline the need for alternative therapies for cisplatin-ineligible patients.