The Social Environment and Colorectal Cancer in the United States

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Project Summary/Abstract The overarching goal of this proposal is to evaluate the relationship between the social environment and health disparities in colorectal cancer (CRC) in the United States, and determine the role of public health policy in reducing them. CRC is the third most common cancer in women and men in the US, and it is the second leading overall cause of cancer mortality, with a total of 53,200 deaths estimated for 2020. While improvements in screening uptake, advances in treatment and reduction of risky behaviors have resulted in lowering CRC incidence and mortality in recent years, people of low socioeconomic status (SES), racial/ethnic minorities, and those without health insurance still have a greater burden of CRC. Due to the interplay of all these characteristics, it is challenging to unpack the role of SES as a driver of CRC health disparities. Recent developments in cancer research have highlighted the need for evaluating neighborhood-level and other social level factors, in addition to individual characteristics as they capture information on access to resources that are key elements of cancer risk, such as: transportation, recreational places, healthy food, healthcare services and education and employment opportunities. The Index of Concentration at the Extremes (ICE) permits the measurement of different aspects of spatial and social polarization, including racial/ethnic, economic and racialized economic residential segregation, and provide a comprehensive assessment of the social environment of individuals. In 2014, the implementation of Medicaid expansion under the Patient Protection and Affordable Care Act (ACA), made health insurance coverage accessible to people of low income, and was expected to reduce CRC health disparities. Prior research evaluating the early years of ACA has shown an increase in insurance coverage, but studies evaluating its effect on CRC screening, incidence and stage at diagnosis have had inconsistent results, and it is not well-understood within racial/ethnic groups. Therefore, this study will use data from a nationally representative sample of adults in the National Health Interview Survey for years 2010-2018, and the United States Cancer Statistics database for 2009-2017, which includes all incident cancer cases in the country, to employ multilevel modeling and econometric methods with these specific aims: 1) determine the presence of health disparities in CRC screening, incidence and stage at diagnosis and 2) elucidate the role of Medicaid expansion in reducing these health disparities. Results from this study will be valuable in informing the effect of health policy and for which groups CRC interventions are most needed to contribute to the NCI mission of “helping all people live longer, healthier lives”. The interdisciplinary training environment and the expert mentorship team for this proposal will provide the applicant an excellent training opportunity to develop methodological and content expertise for a future career as cancer epidemiologist and health disparities researcher.