The Impact of the Affordable Care Act on Racial/Ethnic Disparities in Cancer Diagnosis and Outcomes

This study assesses the extent to which the Affordable Care Act (ACA) Medicaid expansion
reduced racial/ethnic disparities in cancer diagnosis and outcomes. Cancer is responsible for 22
percent of all deaths in the United States, making it the second leading cause of death in the
country, behind only heart disease. There exist large disparities in cancer detection, treatment,
and mortality rates by race/ethnicity: Black and Hispanic cancer patients are on average
diagnosed at later stages than White patients, and mortality rates are higher for non-Whites. One
reason for these disparities may be lack of health insurance. Non-White people are less likely to
be insured, and uninsurance is a major financial barrier to cancer screening, early diagnosis, and
treatment. One of the goals of the ACA was to reduce racial/ethnic disparities in cancer
outcomes by expanding health insurance.

Under the ACA, states have the option to extend Medicaid coverage to low-income people below
138 percent of the federal poverty level. To date, 31 states and DC have opted to expand
Medicaid. We exploit this variation in Medicaid expansion across states and over time to
estimate the causal effect of Medicaid on racial/ethnic disparities in cancer outcomes. Our
primary data source is the National Cancer Institute’s Surveillance, Epidemiology, and End
Results (SEER) program. The SEER reports information on all patients with cancer in
participating areas in the United States, including patient demographics, county of residence,
type of cancer, stage of diagnosis, and type of treatment. The data is nationally representative
and covers 28% of the US population. We augment the SEER data with county-level
uninsurance rates and demographic information from the Census Bureau and county-level cancer
mortality rates from the National Vital Statistics System.

We estimate difference-in- differences (DD) models, comparing changes in cancer outcomes
among people in Medicaid expansion states vs. non-expansion states, before and after the
implementation of the expansion to examine the expansion’s impact on stage of cancer diagnosis
(e.g. early vs. late stage), type of treatment that patients received, and county-level cancer
mortality rate (e.g. number of cancer deaths per 100,000 population in the county). We estimate
these impacts first for the entire population and then separately for each racial/ethnic group to
assess whether the Medicaid expansion closed disparities. We find evidence that the ACA
increased rates of early cancer diagnosis among Black and Hispanic populations. These results
fill a critical void in our understanding of Medicaid’s role in reducing racial/ethnic disparities in
cancer diagnosis and outcomes.