Abstract Introduction: To ensure clinical trial findings are broadly applicable, participants must reflect all affected populations. Geographic distribution of trial participants is shaped by access to trials, physician referrals, service quality, and cancer center reputation. We aimed to characterize participants in cancer clinical trials at the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center (SKCCC) by ZIP-code level factors, including distance, travel time, and sociodemographic characteristics, to identify barriers to equitable participation. Methods: This cross-sectional study used data from 16,010 SKCCC interventional cancer trial participants (2010–2019), including ZIP code of residence, treatment site, cancer type, race, age, and sex. Participants were geocoded to ZIP Code Tabulation Areas (ZCTAs). The CDC Social Vulnerability Index (SVI) served as a proxy for social determinants of health. Population-weighted ZIP code centroids and U.S. Census data were used to calculate distances to trial sites. The key exposure was ZCTA-level distance to SKCCC trial sites, and the primary outcome was the number of participants per ZCTA. We used log-binomial regression to assess associations. Results: Most participants were from Maryland (57%) or neighboring states (86% total), with 14% from 44 other states. Mean distance to trial sites was 29 miles for Maryland residents, 48 miles for neighboring states, and 121 miles overall. Trial participation was higher in ZCTAs closer to SKCCC locations. Mean SVI values were 0.310 overall, 0.300 in nearby states, and 0.350 in distant ones. In adjusted models, greater participation was associated with Maryland or neighboring state residence (IRR: 1.210; 95% CI: 1.140–1.290) and older age (IRR: 1.001; 95% CI: 1.000–1.002). Participation was inversely associated with distance (IRR: 0.999; 95% CI: 0.999–1.000), Hispanic ethnicity (IRR: 0.830; 95% CI: 0.745–0.924), and non-White race—Black (IRR: 0.890; 95% CI: 0.850–0.930), Asian (IRR: 0.770; 95% CI: 0.700–0.850), and Other (IRR: 0.808; 95% CI: 0.740–0.880). Participants at Bayview (IRR: 0.710; 95% CI: 0.630–0.800), Suburban (IRR: 0.670; 95% CI: 0.540–0.830), Sibley (IRR: 0.800; 95% CI: 0.720–0.880), and Green Spring (IRR: 0.630; 95% CI: 0.320–1.260) sites were less likely to enroll than those at the main SKCCC location. No significant associations were observed for SVI or gender. Conclusions: Trial participation at SKCCC was shaped by geography, race/ethnicity, and trial site. Residents living closer to SKCCC, those in nearby states, and non-Hispanic White individuals were more likely to participate. Future work will explore barriers to participation in disease-specific trials. Citation Format: Mehrnoosh M. Soori, Michael R. Desjardins. Spatial disparities in cancer clinical trial accrual: Insights from Johns Hopkins Sidney Kimmel Comprehensive Cancer Center abstract. In: Proceedings of the 18th AACR Conference on the Science of Cancer Health Disparities; 2025 Sep 18-21; Baltimore, MD. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2025;34(9 Suppl):Abstract nr B003.
Soori et al. (Thu,) studied this question.