MARQUETTE — Three Upper Peninsula counties have a disproportionately high rate of colorectal cancer, according to a new study.

Gogebic, Alger and Baraga counties were among the counties with the highest rates, joining Montmorency County, followed by Clare, Gratiot, Oscoda and Osceola counties.

The study by Michigan State University faculty and a surgical resident at Corewell Health in Grand Rapids appeared in the journal Cancer Causes & Control.

In addition, residents of three agricultural counties in the Thumb appear on the list of highest incidence of CRC. They are Huron, Sanilac and Tuscola counties

“Genetics play a role in about 20% of cases,” MyMichigan Health colon-rectal surgeon Sarah Diaz of Midland wrote in a recent newspaper column. She is not associated with the new study.

Colorectal cancer is the third-leading cause of cancer death in the United States. While Michigan’s death and incidence rates are similar to the national average, those rates in Huron, Sanilac and Tuscola counties are above both the state and national figures.

“Findings suggest that living in Michigan’s Thumb region is associated with higher incidence and mortality compared to Michigan’s other rural and urban regions,” the study said.

And while mortality rates in the state have declined considerably during the past several decades, rates in the Thumb “have stayed stagnant for roughly 40 years,” the study said.

Elsewhere in Michigan, the lowest incidence rate for the 2016-20 period was in Houghton County, followed by Emmet, Mason, Ottawa and Ontonagon counties, according to the latest data from the Centers for Disease Control and Prevention.

Wexford and Mecosta counties were among the 10 with the lowest rates.

The MSU study’s lead author, Allison Hoppe, said more research is needed, including examination of environmental factors and differences in treatment.

“It’s somewhat premature to design targeted outreach and programs to reduce the colorectal cancer rate based on this ecological study,” Hoppe said. “However, our findings emphasize the large impact of obesity and smoking.”

Results of the research demonstrate the importance of colonoscopies to screen for colorectal cancer among people over 50, the report said.

“Findings suggest that living in Michigan’s Thumb region is associated with higher incidence and mortality compared to Michigan’s other rural and urban regions,” the study said.

A better understanding of the risk factors could improve prevention efforts, such as persuading people in rural areas to lose weight and eat more healthy foods, it said.

Hoppe said, “Efforts to promote healthy lifestyles, including improving access to healthy foods and smoking cessation are critically important for reducing the burden in Michigan.”

In addition, the director of the public health district for the area, Mark Hamed, said his agency has taken steps to improve access to fecal testing in the region.

“Testing serves as a primary screening tool, allowing for early identification and intervention thus greatly improving prognosis and outcomes,” Hamed said.

Local health departments are also working closely with general practitioners and specialists to help patients manage and treat the disease, he said.

In addition , he said, “we are actively focusing on risk factor reduction, encompassing awareness campaigns and community outreach programs aimed at improving modifiable risk factors,” such as tobacco and alcohol use, physical activity, diet and weight.