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

Abstract

488 Background: Elective 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 chemoradiotherapy (WP-CCRT) compared to bladder-only (BO)-CCRT has not been demonstrated. Currently, the National Comprehensive Cancer Network (NCCN) guidelines do not recommend whether to include pelvic nodes in the radiation field. Using real-world data from the National Cancer Database (NCDB), we sought to compare the overall survival (OS) between BO-CCRT and WP-CCRT for MIBC. Methods: Using the 2019 NCDB Participant User File, we identified cases of MIBC diagnosed between 2017 and 2018. We selected patients with clinical T2-T4N0M0 disease receiving TMT as first-line treatment. TMT was defined as transurethral resection of bladder tumor followed by CCRT: 60–65 Gy of RT delivered to the bladder with concurrent single- or multiple-agent chemotherapy. Patients were stratified into BO-CCRT vs. WP-CCRT. Overall survival (OS) analysis was performed using Kaplan-Meier estimates and multivariable Cox proportional hazards regression analysis. The variables included in the multivariable Cox regression model were age, sex, race, comorbidity burden (as per the Charlson-Deyo comorbidity index), facility type, insurance status, median income quartile, rurality, distance from facility, and clinical T stage. Results: A total of 605 patients receiving TMT for MIBC were identified: 162 (26.8%) BO-CCRT and 443 (73.2%) WP-CCRT. The median follow-up time was 25.6 months (interquartile range [IQR]: 4.8-42.6) and 28.7 months (IQR: 3.0-51.6) for BO-CCRT and WP-CCRT, respectively. The median OS was 32.9 months (95% confidence interval [CI] 30.8 – not reached) and 48.3 months (95% CI 39.6 – not reached) for BO-CCRT and WP-CCRT, respectively. However, multivariable Cox regression analysis failed to find an association between WP-CCRT (hazard ratio [HR] 1.08, 95% CI 0.76-1.54) and improved OS, compared to BO-CCRT. Conclusions: Elective nodal-irradiation (WP-CCRT) in the setting of TMT for MIBC was not associated with a benefit in OS compared to BO-CCRT.