Geographic disparities in access to oncologists and association with cancer mortality rates in the United States.

Abstract

80 Background: Geographic access to oncologists varies across the US and has been particularly constrained in rural areas. To date, the trend of the relationship between oncologist geographic access and county-level cancer mortality, and how it varies by rurality is not well characterized. Methods: Oncologists were identified from the American Medical Association Physician Masterfile for 2010 and 2020 and geocoded by ZIP code. We calculated county-level geographic accessibility scores to oncologists using the enhanced two-step floating catchment area method. Higher scores indicate greater access within a 60-minute driving distance, weighted by population size and oncologist count. Age-adjusted county-level cancer mortality was obtained from the National Center for Health Statistics for 2011-2013 and 2019-2023. Rural/urban status was defined using the U.S. Department of Agriculture Rural-Urban Continuum Codes. Multivariable linear regression examined associations between oncologist accessibility and cancer mortality rates, adjusting for sociodemographic factors. Analyses were stratified by rurality, and interaction terms were tested. Results: A total of 25,899 oncologists were identified in 2010 and 39,869 in 2020. Oncologist accessibility increased from 2010 to 2020 overall, with the median accessibility score rising from 33.5 (IQR, 17.8-55.2) to 39.0 (IQR, 20.3-66.2) (Table). Accessibility was higher in urban than rural counties. Higher accessibility was associated with lower age-adjusted cancer mortality rates in both study periods, with every 1-unit increase in accessibility score associated with adjusted rate differences of -5.6 (95% CI: -7.7, -3.4) and -8.6 (95% CI: -11.1, -6.2) per 100,000 in 2010 and 2020, respectively (p-values <.0001). The association was stronger in rural counties in 2020. Conclusions: Oncologist accessibility increased from 2010 to 2020, but disparities persisted, particularly in rural counties. Higher accessibility was associated with lower age-adjusted cancer mortality rates, highlighting the importance of geographic access to oncologists in improving cancer outcomes. County-level oncologist accessibility scores and associations with age-adjusted mortality rate by urban–rural status. Overall Urban Rural Accessibility score, Median (IQR) 2010 33.5 (17.8, 55.2) 37.0 (20.4, 61.1) 21.6 (10.8, 34.9) 2020 39.0 (20.3, 66.2) 43.3 (23.4, 73.4) 23.9 (12.4, 41.2) Adjusted mortality rate difference p for interaction 2010 −5.6 (−7.7, −3.4) −5.9 (−8.1, −3.8) −8.2 (−25.8, 9.4) 0.6 2020 −8.6 (−11.1, −6.2) −7.9 (−9.8, −5.9) −12.9 (−31.4, −5.6) 0.0001 Note: Models adjusted for county-level social deprivation index, percentage uninsured, percentage aged ≥65 years, Medicaid expansion and urban/rural status.