Gene Could Link Obesity, Colon Cancer (HealthDay)

TUESDAY, Sept. 30 (HealthDay News) -- Researchers have uncovered agenetic link between obesity and the risk for colon cancer. The discoverycould lead to greater accuracy in predicting who is at risk for thedisease, experts say.

Research has suggested that colon cancer risk rises with increasingweight, but this finding points to a genetic reason for the link.

"We have discovered that a genetic variant of the adiponectin gene,called ADIPOQ, is associated with colon cancer risk," said lead researcherDr. Boris Pasche, director of the division of hematology and oncology atthe Comprehensive Cancer Center of the University of Alabama atBirmingham. "This genetic variant may identify individuals who have ahigher risk to develop colorectal cancer," he said.

The report was published in the Oct. 1 issue of the Journal of theAmerican Medical Association.

For the study, Pasche's team focused on ADIPOQ. This gene promotes theformation of a fat hormone called adiponectin. People who inherit a commonvariant of the gene have up to a 30 percent lower risk of colon cancercompared with people without this gene variant, the study found.

On the other hand, the researchers believe that people who donot have this gene variant, or those who have high levels ofadiponectin in their blood, may be at a slightly increased risk for coloncancer and could benefit from early screening for the disease.

"Adiponectin, a hormone exclusively secreted by the adipose [fat]tissue, is now genetically linked with colorectal cancer," Pasche said."This is the first evidence that genetic variants of a 'fat hormone'affect risk of colorectal cancer," he said.

Whether people without this gene variant can reduce their risk of coloncancer through diet and exercise isn't clear, the researchers noted.

"This adds a little bit more to our understanding of one place wheregenetics plays a role in colon cancer development," said Dr. DuradoBrooks, director of colon and prostate cancer prevention programs at theAmerican Cancer Society. "It helps point us in some more specificdirections; it adds another piece to the puzzle," he said.

Brooks does not believe that the finding is definitive, however. "Itsupports some of the other work that has already been done, identifyingthis particular gene region with colorectal cancer," he said.

The finding does help clarify one element linking obesity and coloncancer, but "there is no clinical application to this finding in theimmediate future," Brooks said. "I don't think we would alter anyrecommendation, other than encouraging people to maintain a healthyweight."

Dr. Georgia Wiesner, a cancer geneticist at University Hospitals' CaseMedical Center in Cleveland, agreed.

"I'd love to say that any time we find a new gene that identifies riskor alters risk we would be able to put that into a new drug treatment orat least identify people who are more at risk," Wiesner said. "But in thisstudy, it might just tease out the pathogenesis of disease," she said.

It's already known that people who are obese have a higher risk forcolon cancer, Wiesner said. "I don't know that telling somebody they mighthave a specific marker is really going to alter what they are going todo," she said. "It doesn't mean that these people don't need regularscreening."

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