Geographic access to lung cancer screening and environmental lung cancer risk factors in the contiguous United States

Abstract

Objective: Lung cancer is the leading cause of cancer mortality in the U.S., and worldwide. We examined the association between geographic access to lung cancer screening facilities (LCSF) and geographically distributed lung cancer risk factors - fine particulate matter (PM_2.5) and indoor radon levels in the contiguous U.S.

Methods: We estimated geographic access to LCSF using facility information from the American College of Radiology, Lung Cancer Screening Registry and the enhanced two-step floating catchment area method. Census tract level PM_2.5 and county level radon data were obtained from the U.S. EPA. We examined whether PM_2.5 and radon predicted geographic access to LCSF using a linear mixed effects model with random intercepts for counties, adjusting for smoking prevalence and other factors, and testing for modification by urban-rural area.

Results: We found higher geographic access to LCSF in counties with moderate and high radon levels, and census tracts with higher levels of PM_2.5, with significant modification by urban-rural areas.

Discussion: Our results suggest that accessibility to LCSF in the U.S. is generally aligned with environmental risk factors for lung cancer, with the exception of micropolitan areas or small cities, where higher PM_2.5 areas had lower screening access. It is worth considering how environmental risk factors may be incorporated into lung cancer screening programs.

Keywords: Geographic accessibility; Lung cancer screening; PM(2.5); Radon; Spatial access index.