Treatment Facility Volume and Survival in Patients with Advanced Prostate Cancer

Abstract

Background: Despite improvements in medical management of advanced prostate cancer (aPC), it continues to be a leading cause of cancer death in men. Contemporary management of men with aPC is complex and requires resources to be more readily available at high-volume facilities. Objective: To determine the relationship between facility volume and survival in men with aPC. Design, setting, and participants: The National Cancer Database (NCDB) was queried from 2004 to 2013 for aPC, defined as T4, N+, or M+ disease, identifying 64 815 patients. Six predefined patient cohorts were evaluated. Cohort “A” included all patients with aPC. “B” cohorts included only M0 patients. “C” cohorts included only M1 patients. Facilities were divided into quartiles based on median treatment volume (patients/yr). Intervention: Diagnosis and management of aPC at an NCDB-reporting facility. Outcome measurements and statistical analysis: Overall survival (OS) was assessed as a function of facility volume. Multivariable Cox regression models were fitted. Cox regressions using natural cubic splines were used to test for nonlinear relationships between volume and OS. Results and limitations: OS improved as facility volume increased (top quartile vs bottom quartile, hazard ratio 0.82, 95% confidence interval 0.77–0.88, p < 0.001) and was consistent across patient cohorts. Spline models demonstrate a continuous decrease in hazard of death as volume increases. Limitations include the retrospective analysis and a lack of precise treatment information. Conclusions: In this retrospective analysis of nearly 65 000 men who presented with aPC, we demonstrate an association between higher facility volume and improvements in OS. This OS advantage persisted with similar magnitudes of effect after narrowing the cohorts by disease and treatment characteristics. Patient summary: In this retrospective review of the National Cancer Database, we analyzed the association between treatment facility volume and survival in men who are diagnosed with advanced prostate cancer. We found that survival improved as volume increased, indicating a possible imbalance of resources and expertise that favors higher-volume facilities.