A cancer researcher with the University of Minnesota Hormel Institute in Austin has found evidence of a link between obesity and an increased risk of breast cancer in postmenopausal women.

Approximately 40 percent of the 45 million women in the United States between the ages of 45 and 75 are obese.

Margot Cleary, professor of nutrition and metabolism at Hormel Institute and member of the University of Minnesota Cancer Center, led the research team on this laboratory study.

The study is one of the first to investigate the function of a hormone protein called adiponectin is only produced in body fat. The study was done in mice and breast cancer cell lines developed from women of postmenopausal age and diagnosed with breast cancer.

"We found that adiponectin plays a dual role," Cleary says. "Lower blood levels of this protein are associated with higher amounts of body fat. In this case, low adiponectin may help trigger the growth and spread of breast cancer."

Cleary says the message of her finding for postmenopausal women is "maintaining your proper weight may possibly help you reduce your chances of breast cancer."

She adds that the levels of adiponectin may be increased with weight loss through diet or surgery.

Other research has implicated adiponectin in other diseases related to diet, including type 2 diabetes and coronary artery disease.