CHICAGO A gene related to a hormone secreted by the body's fat cells may lower the risk of colon cancer, a discovery that could reassure people with a family history of the disease, researchers said on Tuesday.
The gene variation, shared by about half of all those in the study, likely helps control how much of the hormone adiponectin fat cells secrete, the researchers reported in the Journal of the American Medical Association.
People with more of the hormone in their blood are known to have a lower risk of colon cancer, but the body's mechanism for controlling adiponectin secretion by cells is unclear.
The hormone suppresses inflammation of blood vessels, can raise the body's metabolic rate, and is known to lower the risk of colon and breast cancer.
Obese people, who have a higher risk of cancer, tend to have less of the hormone. People with more adiponectin have less risk of heart disease and diabetes.
The researchers reported on two groups totaling 1,500 people.
New Yorkers of Ashkenazi Jewish ancestry who had the gene were 28 percent less likely to have been diagnosed with colon cancer. The disease is more common in Ashkenazi Jews -- who originated in Europe -- than the general population.
The other group, from Chicago, was diverse ethnically and those with the gene had a 52 percent lower risk.
"Is this the (genetic) snip that is the cause of the disease? Most likely not. It just gives us a region on the gene where we think the association to colorectal cancer risk stems from," said Dr. Boris Pasche of the University of Alabama at Birmingham. Pasche led the research, done primarily while he was at Northwestern University in Chicago.
Colon cancer will be diagnosed in 149,000 Americans this year and will kill 50,000, according to the American Cancer Society. Globally, about 1.2 million cases of colorectal cancer are diagnosed annually and the disease kills about 630,000 people.
Family history accounts for about one-third of colon cancer cases, and several other genes have been linked with colon cancer, but the genetic component is unknown for most.
Other risk factors include a diet high in fat and calories and low in fiber; obesity; a sedentary lifestyle; heavy drinking and smoking.
Tracing the genetic source of diseases such as cancer is in its infancy, but holds promise. If diagnosed early, colon cancer is highly treatable, Pasche said.
(Editing by Maggie Fox)