Association Between Treatment at a High-Volume Facility and Improved Survival for Radiation-Treated Men With High-Risk Prostate Cancer

Abstract

Purpose: Although the association between higher hospital volume and improved outcomes has been well-documented in surgery, there is little data about whether this effect exists for radiation-treated patients. We investigated whether treatment at a radiation facility that treats a high volume of prostate cancer patients is associated with improved survival for men with high-risk prostate cancer.

Methods and materials: We used the National Cancer Database (NCDB) to identity patients diagnosed with prostate cancer from 2004 to 2006. The radiation case volume (RCV) of each hospital was based on its number of radiation-treated prostate cancer patients. We used propensity-score based analysis to compare the overall survival (OS) of high-risk prostate cancer patients in high versus low RCV hospitals. Primary endpoint is overall survival. Covariates adjusted for were tumor characteristics, sociodemographic factors, radiation type, and use of androgen deprivation therapy (ADT).

Results: A total of 19,565 radiation-treated high-risk patients were identified. Median follow-up was 81.0 months (range: 1-108 months). When RCV was coded as a continuous variable, each increment of 100 radiation-managed patients was associated with improved OS (adjusted hazard ratio [AHR]: 0.97; 95% confidence interval [CI]: 0.95-0.98; P<.0001) after adjusting for known confounders. For illustrative purposes, when RCV was dichotomized at the 80th percentile (43 patients/year), high RCV was associated with improved OS (7-year overall survival 76% vs 74%, log-rank test P=.0005; AHR: 0.91, 95% CI: 0.86-0.96, P=.0005). This association remained significant when RCV was dichotomized at 75th (37 patients/year), 90th (60 patients/year), and 95th (84 patients/year) percentiles but not the 50th (19 patients/year).

Conclusions: Our results suggest that treatment at centers with higher prostate cancer radiation case volume is associated with improved OS for radiation-treated men with high-risk prostate cancer.