Distribution and Geographic Accessibility of Prostate Cancer Clinical Trials in the United States

59 Background: An extremely small proportion of patients with cancer in the United States (US) enroll in clinical trials. While several barriers to trial accrual have been described, the geographic distribution and accessibility of clinical trial sites has not been comprehensively explored. Methods: ClinicalTrials.gov was queried to identify all active US clinical trials exploring first-line therapies for metastatic prostate cancer (PCa) on 9/16/2012. We evaluated the geographic distribution of trial sites and determined the relationship between the number of sites and the number of patients with advanced PCa per county and evaluated heterogeneity using Lorenz curves. We also estimated the minimum driving distance required to access a clinical trial site from each ZIP code in the continguous US; a distance >30 miles was defined as high travel burden consistent with prior studies. Results: We identified 958 sites associated with 42 PCa clinical trials (Table). The geographic distribution of clinical trial sites was very inhomogeneous with several states having only 1-2 trial sites. Among 3185 US counties, 2,669 (83.8%) had no clinical trials available for first-line treatment of metastatic PCa. Counties with larger populations of patients with advanced PCa had significantly higher numbers of clinical trial sites. For every 100 additional patients with advanced PCa per county, the number of available trial sites increased by 21.0% (95% CI: 16.5-25.7%). However, Lorenz curves indicated a high degree of inequality in trial accessibility (Gini index 0.71). Approximately 31% of the US population resided >30 miles from a PCa trial site. Conclusions: Clinical trials sites are poorly accessible, geographically, to a large subset of US PCa patients, a finding that likely contributes to dismal accrual. Innovative solutions are required to address geographic barriers to access. [Table: see text]