State-run Medicaid insurance, expanded in 2014 as part of the Affordable Care Act, has resulted in decreased metastatic cancer incidence rates as well as decreased overall cancer mortality rates and averted over one thousand deaths due to cancer per year. About 12% of the improvements in cancer mortality were due to decreases in metastatic diagnoses, according to a study presented as part of the 2022 ASCO Quality Care Symposium. 

The researchers determined that being able to diagnose cancer at an advanced or distant stage had an important impact on cancer mortality rates, supporting the hypothesized mechanism that Medicaid expansion led to a shift towards earlier diagnoses, resulting in improved prognoses and ultimately fewer cancer deaths.

Contrary to expectations at the start of the study, the researchers did not see any expansion-associated changes in localized cancer incidence rates.

“Perhaps the most surprising finding in our study was the lack of change in localized cancer incidence rates in states with Medicaid expansion as it has been believed that the expansions might have increased access to cancer screening and enabled patients to see a physician earlier for cancer-related symptoms. Some studies have shown that Medicaid expansion effects on localized cancer incidence rates dissipate over time, which is perhaps consistent with our findings looking at the entire post-expansion period from 2014 until 2019 in aggregate,” said lead author Justin Michael Barnes, MD, who is a resident in the Department of Radiation Oncology at the Washington University School of Medicine in St. Louis.

Expansion of state-run Medicaid programs was enabled by passage of the Affordable Care Act in 2014. Earlier studies have shown that the expansion led to earlier cancer diagnoses and improved cancer survival in many states. However, it has been uncertain if the expansion-associated survival benefits were driven primarily by early detection leading to improved prognosis or increased access to appropriate cancer care.

For their study, the researchers obtained state-level cancer incidence and mortality data from 2001-2019 for people 20-64 years of age. Analyses were conducted to compare changes in localized and distant stage cancer incidence rates and cancer mortality rates from pre- and post-2014 expansion vs. non-expansion states. The data were stratified by age, sex, and race.

For all cancer sites combined, there was about a 3.3% decrease in the distant stage cancer incidence rate and about a 3.5% decrease in the cancer mortality rate in expansion states relative to non-expansion states. These estimates translated to 2,612 averted distant stage cancer diagnoses and 1,031 averted cancer deaths per year in the Medicaid expansion states. About 12% of those improvements in cancer mortality were calculated to be due to decreases in metastatic diagnoses. By cancer site, there were Medicaid expansion-associated decreases of about 3.6% in cancer mortality rates for breast cancer and about 6.0% for cervical cancer.

While this study shows the impact of expansion affecting improved distant-stage diagnoses, there were no changes in localized cancer incidence rates that might have also been expected by expansion-led efforts to increase screening and early detection.


The researchers note that five additional states expanded Medicaid after the end of the study period in late 2019. Assuming a relatively similar impact of expansions in these states as in the ones that were studied, the researchers expect a larger number of averted distant stage cancer diagnoses and cancer deaths. However, the investigators note that future analyses incorporating data after 2019 will face the challenges of interpreting changes in the context of the COVID-19 pandemic.

The researchers also hope to examine other potential mediators of Medicaid expansion-associated changes in overall survival, such as timely receipt of therapy and quality of treatment.

“Medicaid expansion has clearly saved thousands of lives that would have been lost to cancer, as this new study shows. But insurance expansion can only move the needle so far and can’t alone overcome structural barriers rooted in the social determinants of health that many patients face. Interventions that support care for marginalized populations should be considered along with Medicaid expansion efforts,” said ASCO chief medical officer and executive vice president Julie R. Gralow, MD, FACP, FASCO.

This news item is adapted from an ASCO news release published on September 26, 2022.