A research team led by Mayo Clinic physicians has found that older women with diabetes face a more than doubled risk for some types of colorectal cancer.
Colorectal cancer remains the third-leading cause of cancer deaths among women in the United States. Diabetes has been identified as a colon cancer risk factor, but the mechanisms are not completely understood. For this population-based cohort study, researchers examined data from 37,695 participants of the Iowa Women’s Health Study (IWHS), which enrolled women ages 55years to 69years of age in 1986 and remains ongoing. Of these women, 2,361 reported a diagnosis of Type 2 diabetes and 1,200 developed colorectal cancer.
To find the links between colorectal cancer and diabetes, researchers worked with regional pathology laboratories to obtain tumor tissue samples from IWHS participants who were diagnosed with colorectal cancer. They linked the tissue samples with other IWHS data, looking for cancer pathways and risk factors, and whether those risk factors were associated with three different molecular markers: microsatellite instability (MSI), CpG island methylation (CIMP), and BRAF gene mutations.
“Diabetes was more strongly associated with the MSI-high, CIMP-positive and BRAF-mutation cancer subtypes in this group of older women,” Paul Limburg, MD, Mayo Clinic gastroenterologist, said in a news release.
Limburg explains that diabetes appeared to confer a greater than twofold increase in risk for these molecularly-defined tumors, compared to women without diabetes.
“Knowing that diabetic women have these findings should help to facilitate more appropriate colorectal cancer prevention and treatment options,” Anthony Razzak, MD, a Mayo Clinic research fellow stated. “Our findings may lead to new strategies for colon cancer screening, chemotherapy and chemoprevention in women with diabetes. From a research perspective, this information allows us to clarify how environmental exposures and other risk factors might affect tumor formation at a molecular level.”