Yale researchers have shown a correlation between cancer mortality and the inequality in income of U.S. counties.

The study determined that higher-income counties have a lower mean cancer death rate and found that this phenomenon may be mediated by differences in health risk behavior, clinical care factors, health environment and health policies. These factors provide possible specific targets for public policy interventions to reduce cancer mortality rates and lessen disparities, according to the researchers. The study was published in the journal JAMA Open on Oct. 5.

“There is a tension that is felt when you see rapid advances in therapies for certain cancers at the same time as you see cancer death rates rising in certain communities,” said Jeremy O’Connor, physician at Yale New Haven Hospital and lead author of the study. “It made us worry that increasingly, there were communities that were being left behind or left out.”

While income disparity is determined by forces larger than the medical and public health community, or any individual senator, the results from this study provide various possibilities for public policy, according to School of Medicine professor Cary Gross, the senior author of the study.

For example, he suggested, potential programs to lower smoking and investments to build safe and accessible recreational areas to promote physical activity can narrow this gap in cancer mortality.

The disparity in cancer mortality between high-, medium- and low-income counties can appear overwhelming, Gross said.

“A first step is to identify levers of change — what can potentially be done to move things in the right direction?” He said. “That was one of our motivations for this study.”

Individual doctors can educate their patients based on their counties’ specific risk factors – such as high rates of smoking and unaffordable care. They can also use these risk factors to advocate for local health policies, such as state smoke-free laws or higher Medicaid payment rates, according to the study.

“By starting with specific programs for specific factors, it might be possible for us to chip away at the long-standing structural problems, such as racism, that lie at the root of certain disparities,” O’Connor said.

O’Connor added he was most surprised by the strength of the association with food insecurity. Food insecurity is often associated with obesity and other health outcomes, he explained, but there is less evidence about its association with cancer mortality.

The study also discovered that variability in cancer mortality exists even within the groups of lower-income counties. So, further studies can be performed to explain why certain counties are doing better with similarly scarce resources, Gross said.

Another future direction for the researchers is studying a large cohort of patients across the counties that can be followed up over time to assess the risk factors at an individual level, O’Connor said.

He noted that this study was an observational study, only reflecting the present moment in time.

The 2016 21st Century Cures Act authorized $1.8 billion to fund former Vice President’s Joe Biden Cancer Moonshot over a seven-year period.

Ann Hui Ching | annhui.ching@yale.edu .

Correction: A previous version of the article stated physicians could advocate for lower Medicaid payment rates. In fact, they would advocate for higher rates.