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.