Association of treatment facility case volume with survival in patients undergoing radiotherapy/chemoradiotherapy for muscle-invasive bladder cancer: An analysis of the National Cancer Database.

Abstract

295 Background: Excellent outcomes with bladder-preserving trimodality therapy have been demonstrated at centers with expertise and high-volume. Some argue that these results may not be replicated at other centers with lower case volumes. We analyzed the National Cancer Database to determine if treatment at a high-volume facility is associated with improved overall survival (OS) for patients undergoing radiotherapy (RT) or chemoradiotherapy (CRT) for non-metastatic muscle-invasive bladder cancer (MIBC). Methods: Patients with cT2-4 N0-3 M0 transitional cell MIBC treated with RT or CRT were selected. The case volume variable was derived by calculating a count of patient records by each facility using the entire database of 439,188 patients. Multivariate analysis (MVA) was performed using the Cox proportional hazards model, which was used to assess the association of case volume with OS while controlling for clinicodemographic and treatment factors associated with OS on univariate analysis, including clustering of patients within their treatment facility type. Results: 872 patients treated with radiotherapy from 2008-2012 at 452 unique facilities were identified. 502 (58%) patients received RT, and 370 (42%) patients received CRT. The median case volume at each unique facility was 376 cases with an interquartile range of 235 – 579 cases. In the entire radiotherapy cohort, MVA controlling for patient case load, age, sex, education, T Stage, N Stage, cumulative radiotherapy dose, Charlson-Deyo comorbidity score, and geographic location, demonstrated that treatment at a facility with a higher case volume was associated with improved OS. For every 250 patient increase in facility case volume, the hazard of death at any given time for patients receiving radiotherapy decreased by 7% (HR = 0.93, 95% CI: 0.87 – 0.98, p = .01). Conclusions: To the authors’ knowledge, this is the first analysis demonstrating an association between treatment facility case volume and OS in the treatment of MIBC patients with RT or CRT. Consideration should be given to referring patients to high volume facilities for treatment of MIBC.