Effect of Radiation Treatment at a High-Volume Center on Outcomes in Intermediate-Risk Prostate Cancer: An Analysis of the National Cancer Database.

Objective: To investigate the effect of radiation treatment at a high-volume center on overall survival in men with intermediate-risk prostate cancer.

Methods: From 2004 to 2015, 430,347 patients with intermediate-risk prostate cancer were identified in the National Cancer Database. Radiation case volume (RCV) of each hospital was calculated based on number of patients treated. After excluding certain patients including those with metastatic disease, our final analysis population included 116,091 intermediate-risk prostate cancer patients receiving radiation therapy or radiation with androgen deprivation therapy. Characteristics analyzed include age, race, distance to treatment facility, Charlson-Deyo Score, and socioeconomic factors. Primary outcome was overall survival (OS). Five-year survival rates were estimated using the Kaplan-Meier method. Adjusted hazard ratios with 95% confidence intervals were computed using multivariate analysis. Cox regression and propensity score-matched analysis was performed.

Results: Median follow up was 63.5 months and estimated 5-year OS was 90.1% at high RCV centers and 88.2% at low RCV centers (P <.0001). Treatment at high RCV facility was associated with significantly lower mortality compared to treatment at a low RCV facility on multivariate analysis and propensity score matching analysis. The survival benefit of treatment at a high RCV facility remained when high RCV facilities were defined as those above the 80th, 90th, and 95th percentile in patient volume (P <.05).

Conclusion: Treatment at a high radiation case volume facility is associated with improved OS in patients with radiation-treated intermediate-risk prostate cancer. This survival benefit is important to consider when choosing a treatment center for radiation therapy.