Metabolic syndrome -- a risk factor for heart disease and diabetes -- may play a role in the risk of post-menopausal breast cancer, U.S. researchers said.

The metabolic syndrome, or insulin resistance syndrome, consists of a series of factors including abdominal obesity, high blood glucose levels, impaired glucose tolerance, abnormal lipid levels and high blood pressure. It is associated with poor diet and lack of physical activity.

Senior epidemiologist Geoffrey C. Kabat at Albert Einstein College of Medicine in New York and colleagues used existing data from a large, national study designed to assess major causes of chronic disease in women. Participants included post-menopausal women ages 50-79 years at enrollment who had repeated measurements of components of metabolic syndrome over an eight-year period.

Of the 4,888 women with baseline measurements who did not have diabetes, 165 incident cases of breast cancer were diagnosed during the follow-up period. Presence of the metabolic syndrome at baseline was not associated with breast cancer risk.

However, in analyses that made use of the repeated measurements of blood levels of glucose, cholesterol, triglycerides, waist girth and blood pressure, women who had the metabolic syndrome during the three to five years prior to breast cancer diagnosis had roughly a doubling of risk, Kabat said.

The findings were published in Cancer Epidemiology, Biomarkers & Prevention.