Oct. 10 - First-Ever Genetic Link Between Obesity and Colon Cancer Risk Revealed

A new study reveals the first-ever genetic link between obesity and colon cancer risk, a finding that could lead to greater accuracy in testing for the disease, according to a researcher at the University of Alabama at Birmingham. The findings were recently published in The Journal of the American Medical Association.

The discovery also may improve efforts to ward off colon cancer with obesity-fighting activities like exercise, weight loss, and healthy eating.

"Our hope is that we can significantly improve the screening and early detection for this disease and open new avenues for better understanding the genetic and lifestyle factors that influence colon cancer risk," says Boris Pasche, MD, PhD, director of the division of hematology and oncology at the University of Alabama at Birmingham Comprehensive Cancer Center and lead author of the study.

The research focuses on a gene called ADIPOQ that results in the formation of a fat hormone called adiponectin. It shows that those who inherit a common genetic variant of ADIPOQ carry up to a 30% reduced risk of colon cancer compared with others.

In other words, Pasche says, those identified without the gene variant or those who have unhealthy blood levels of adiponectin may benefit from early colorectal testing. Additional studies are needed to confirm whether those without the variant benefit from cancer-prevention lifestyle changes such as diet and exercise.

Colon cancer is the third-leading cancer killer of Americans. This year, 149,000 people will be diagnosed with colon cancer and 50,000 will die from the disease, according to estimates from the American Cancer Society.

One third of people with colon cancer have a clear family history of the disease, and now scientists are homing in on the exact DNA sequences or mutations within the ADIPOQ gene that influence colon cancer risk, Pasche says.

It has already been proven that obesity is influenced by genetics, and colon cancer is influenced by genetics. This study is the first to make a three-way scientific connection between genetic variation, obesity, and colon cancer risk.

Other research has shown adiponectin is associated with diabetes, insulin resistance, cardiovascular disease, and with influencing cell growth in colonic tissues. Exactly how adiponectin or its genes directly impact tumor growth is still unknown, but those cell pathways are being widely studied, Pasche says.

A separate gene variant in ADIPOQ is a known modifier for breast cancer risk, according a recent study in Cancer Research that was coauthored by Pasche.

The Journal of the American Medical Association study was performed with blood samples taken from 1,497 participants, including healthy volunteers and colon cancer patients. It includes both sexes and a mix of age, race, and ethnicity.

Source: University of Alabama at Birmingham

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