Breast cancer screening and outcomes: an ecological study of county-level female Veteran population density and social vulnerability

Abstract

Introduction: Previous studies have shown that breast cancer incidence rates are higher among female Veterans than the general population due to factors such as increased lifetime exposure to breast cancer risk factors or more accurate detection and surveillance. The present study explored relationships between nationally representative county-level breast cancer outcomes, mammography screening rates, female Veteran population density, and social vulnerability. Methods: Data for the present ecological study were obtained at the county level from the United States Census Bureau, the University of South Carolina's Hazards and Vulnerability Research Institute (HVRI), and the National Cancer Institute. We conducted ordinary least squares (OLS) multiple regression analyses to determine the relative influence of female Veteran population density, social vulnerability, and mammography screening rates on breast cancer incidence and mortality rates between 2010 and 2014. County-level covariates such as liquor store density, cigarette smoking prevalence, air pollution, and access to healthy foods, were entered into each model to determine the unique influence of each of the main study variables on breast cancer outcomes. Results: County-level breast cancer incidence rates were higher in counties with greater female Veteran population density, lower social vulnerability, and higher mammography screening rates ( n=2,698, F=33.669, p<0.001). County-level breast cancer mortality rates were higher in counties with lower female Veteran population density, higher social vulnerability, and lower mammography screening rates ( n=1,803, F=18.180, p<0.001). Discussion: The results of the present exploratory study were preliminary, and thus further research on relationships examined in this study are needed. However, because female Veterans were shown to live in counties with relatively high mammography screening rates and lower social vulnerability, their risk for mortality from breast cancer may be lower than for the general population – in particular due to early detection and treatment.