Obesity linked to multiple cancer risks

WASHINGTON -- Heart disease and diabetes get all the attention, but expanding waistlines increase the risk for at least nine types of cancer, too. And with the obesity epidemic showing no signs of waning, specialists say they need to better understand how fat cells fuel cancer.

What's already clear is that being overweight can make it harder to spot tumors early, catch recurrences, determine the best chemotherapy dose, even fit into radiation machines.

That in turn hurts chances of survival. One major study last year estimated that excess weight may account for 14 percent to 20 percent of all cancer deaths -- 90,000 a year.

So why is cancer often the afterthought when listing obesity's multiple risks?

"The cancer picture is a little bit more subtle," said American Cancer Society epidemiologist Eugenia Calle, one of the nation's leading specialists on the link.

Fat is known to increase the risk of developing cancers of the colon, breast, uterus, kidney, esophagus, pancreas, gallbladder, liver, and top of the stomach.

Weight is most strongly linked to cancer of the uterine lining. An overweight woman has twice the risk of developing that cancer as a lean one; once she becomes obese, the risk rises as much as 3.5-fold to 5-fold.

The obese have up to triple the risk of kidney cancer and a type of esophageal cancer as do those of normal weight.

The risk is somewhat smaller among two of the nation's most common cancers.

Overweight or obese men are 50 percent to twice as likely as lean men to get colon cancer. For women, the extra risk is 20 to 50 percent.

Fat is linked to breast cancer in postmenopausal women only, increasing risk of the disease by 30 percent among the overweight and 50 percent among the obese.

For the other four cancers, the obesity risk falls somewhere in between.