Comparative real-world survival outcomes of muscle-invasive bladder cancer treated with bladder-only vs. whole-pelvis concurrent chemoradiation

Introduction: Elective pelvic nodal irradiation for patients with muscle-invasive bladder cancer (MIBC) undergoing trimodal therapy (TMT) is controversial. In patients with node-negative (N0) MIBC, the benefit of elective whole-pelvis concurrent chemoradiation (WP-CCR) compared to bladder-only (BO)-CCR has not been demonstrated. Using real-world data from the National Cancer Database (NCDB), we sought to compare the overall survival (OS) between BO-CCR and WP-CCR for MIBC. Methods: Using the 2020 NCDB Participant User File, we identified cases of MIBC diagnosed between 2017 and 2019. We selected patients with clinical T2-T4aN0M0 disease receiving CCR as first-line treatment. CCR was defined as transurethral resection of bladder tumor followed by ≥40 Gy radiation to the bladder with concurrent single- or multiple-agent chemotherapy. Based on elective nodal irradiation status, patients were stratified as having received BO-CCR vs. WP-CCR. OS analysis was performed using summary three-month conditional landmark, inverse probability treatment weighting (IPTW)-adjusted Kaplan-Meier estimates and Cox regression. Results: A total of 604 patients receiving CCR for MIBC were identified: 367 (60.8%) BO-CCR and 237 (39.2%) WP-CCR. Before IPTW, the groups were imbalanced in terms of baseline characteristics. The median followup of the weighted population was 42.3 months (interquartile range [IQR] 18.1–49.1 months). In IPTW-adjusted Cox proportional hazards regression analysis, WP-CCR was associated with a significant OS benefit compared to BO-CCR (adjusted hazard ratio 0.72, 95% confidence interval 0.54–0.96, p=0.026). Conclusions: In the setting of CCR for N0 MIBC, this retrospective NCDB analysis revealed that WP-CCR was associated with a benefit in OS compared to BO-CCR.