Weight-loss surgery could reduce the risk of a cancer diagnosis in obese patients.

"Bariatric surgery is associated with reduced cancer risk in morbidly obese people [to that of normal-weight people]," the researchers wrote. HealthDay reported.

United States reviewers were not sure if the surgery would help reduce cancer risk in people of a normal weight, but agreed it could reduce risk in obese individuals.

Cancer rated in obese people are about two per every 1,000; bariatric surgery could reduce that rate to one per every 1,000.

"The evidence that obesity is related to an increased risk of cancer is significant, even in the modestly obese. There is an association [between obesity and cancer]. It is a risk factor for cancer development," Doctor Cy Stein, chair of medical oncology and experimental therapeutics at the City of Hope Medical Center, told HealthDay.  

To make their findings the researchers looked at 13 studies that encompassed 54,000 individuals; they focused on cancer rates after weight loss surgery.

About one in three cancer deaths are linked to excess weight, inactivity, and poor eating habits, according to the American Health Society, HealthDay reported.

"I would say overall the evidence appears [to show] there is a reduction in risk," Lauren Teras, director of hematologic cancer research at the American Cancer Society, told HealthDay. "It's just hard to say for certain."

Researchers are not sure of exactly what causes the link between cancer and obesity.

"I think there is some good evidence that hormones play a role," Teras said.

Fat tissue is the largest source of estrogen after menopause, and could contribute to estrogen-related cancers.

"We're not sure if the obesity causes the cancer," Stein said, "but it may promote it."

"Weight-loss surgery, like any surgery, is not without risks. The risks and benefits should be weighed with a person's individual doctor," Teras told HealthDay.