Extra Belly Fat Raises Colon Cancer Risk in Women

NEW YORK APR 19, 2006 (Reuters Health) - Women who carry a lot of weight around their middles are at increased risk for developing colon cancer, according to a report in the International Journal of Cancer.

"Studies of colon cancer risk in males have reported strong positive associations with obesity," particularly when the extra pounds are carried in the abdomen, also known as "central adiposity", Dr. Graham G. Giles, of the University of Melbourne, Australia, and colleagues note.  "The association has been weaker and less consistent for women."

In the current study, the researchers examined the association between body size and shape and the risk of colon cancer in some 24,000 women followed for about 10 years.  Direct body measurements were taken, and bioelectrical impedance analysis was used to estimate fat mass and fat-free mass.  Central adiposity was estimated by waist circumference and waist-to-hip ratio (WHR).

A total of 212 women were diagnosed with colon cancer during follow-up.  The average age at diagnosis was 66 years.  The researchers found that the risk of colon cancer increased as central adiposity rose.

There are a number of possible mechanisms that may explain the association between obesity and colon cancer.  "High levels of physical activity have consistently been shown to reduce the risk of colon cancer and may be linked to the mechanism whereby obesity predisposes to colon cancer," Giles and colleagues state.

Moreover, a fat-related hormone called leptin, "which has been shown to be associated with colon cancer (at least in men), may be another link between obesity and colon cancer."  Leptin has also been shown to stimulate the growth of colon cells in the lab.

SOURCE:

• International Journal of Cancer, March 2006.