Researchers identify cluster of N.C. counties with higher colorectal cancer death rates

UNC Lineberger researchers uncovered county-level factors linked to higher colorectal cancer mortality rates in a cluster of counties in northeastern North Carolina. The study’s first author is Tzy-Mey Kuo, PhD, research associate at UNC Lineberger. Andrew Olshan, PhD, is the study’s senior author.

Researchers identify cluster of N.C. counties with higher colorectal cancer death rates click to enlarge Tzy-Mey Kuo, PhD, is a research associate at UNC Lineberger.
Researchers identify cluster of N.C. counties with higher colorectal cancer death rates click to enlarge Andrew Olshan, PhD, is the study’s senior author.

February 18, 2019

University of North Carolina Lineberger Comprehensive Cancer Center researchers have uncovered county-level factors linked to higher colorectal cancer mortality rates in a cluster of counties in northeastern North Carolina.

In the journal Cancer Epidemiology, researchers report 10 counties in northeastern North Carolina are part of a cluster of counties with higher rates of colorectal cancer mortality. Rather than finding a single factor linked to this pattern, they believe a convergence of several factors is at play.

“Our study found that socioeconomic deprivation interacts with a group of other risk factors at the area level to help shape higher rates of colorectal cancer death rates in these counties,” said the study’s first author Tzy-Mey Kuo, PhD, research associate at UNC Lineberger. “That means when we try to do something to reduce cancer mortality in this target area, we need to think about all of these factors, and design multi-faceted interventions.”

Colorectal cancer is the third leading cause of cancer death in the United States. The national mortality rate has declined dramatically alongside effective screening measures. Yet, a study led by American Cancer Society researchers and published in 2015 in Cancer Epidemiology, Biomarkers and Prevention, identified an 11-county area of northeastern North Carolina as part of “a hotspot” of colorectal cancer mortality for the nation, along with regions in west-central Appalachia and in the lower Mississippi delta.

“In the areas the other researchers defined as ‘hotspots,’ they saw excessive or elevated mortality rates that were significantly higher compared to other counties in the country,” Kuo said. “We were puzzled as to why, and what factors might explain this geographic variation.”

Using data from the U.S. Centers for Disease Control and Prevention and other sources, researchers analyzed colorectal cancer death from 2003 to 2013 to verify whether the cluster existed in North Carolina and to determine if there were specific factors driving the increased mortality rates.

They identified a group of 10 counties that had elevated colorectal cancer mortality rates that were also located adjacent to other counties with elevated rates.

In those counties, an average of 55 people died in each county from colorectal cancer per 100,000 people, with mortality rates as high as 75 per 1000,000 people. By comparison, the overall colorectal mortality rate per county for North Carolina was 45 deaths per 100,000 people.

An analysis of area-level data found a link between higher rates of colorectal cancer deaths and areas with high levels of socioeconomic deprivation, a measurement that incorporates a range of factors, including employment and income. They found that deprivation was linked to higher rates, along with issues of colorectal cancer screening access, obesity, access to adequate and effective healthcare and whether the area was urban or rural.

Kuo said while the study generated important insights by analyzing county-level data, it was not designed to answer questions about how personal factors link to the clusters of higher colorectal cancer mortality.

Andrew Olshan, PhD, senior author of the study, professor in the UNC Gillings School of Global Public Health Department of Epidemiology, and associate director for population sciences at UNC Lineberger, said analytical studies of cancer incidence and mortality in North Carolina will be an increasing function for researchers involved with UNC Lineberger’s emerging community outreach and engagement group and the Carolina Information & Population Health Resource (CIPHR), a robust database researchers can use to investigate the health care, economic, social, behavioral, and environmental factors that influence cancer incidence, mortality, and burden.

“We want to open the hood and drill down to understand cancer mortality and incidence in our state, and what the determinants are,” Olshan said.

In addition to Kuo and Olshan, other authors include Anne Marie Meyer, PhD, adjunct associate professor in UNC Gillings, Christopher D. Baggett, PhD, faculty director for CIPHR.

The study was supported by CIPHR and the University Cancer Research Fund. The study is one of the research projects of the Carolina Cancer Screening Initiative.

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