TUESDAY, Dec. 30, 2008 (HealthDay News) -- Women with high levels of insulin in their blood appear to be more likely to develop breast cancer than those with lower insulin levels.
And that might be the link between obesity and breast cancer, say researchers from the Albert Einstein College of Medicine in New York City. High insulin levels have already been associated with obesity.
The researchers compared insulin levels in 835 women who developed breast cancer and 816 women who did not. All women were participating in the Women's Health Initiative study. Those whose fasting insulin levels were the highest had a 1.5 times greater risk of breast cancer than did women with the lowest fasting insulin levels, the study found.
The risk was even greater among women who were not taking hormone therapy. The study found that those women were 2.4 times more likely to have developed breast cancer if their insulin levels were high than if they were low.
The findings were published in the Dec. 30 issue of the Journal of the National Cancer Institute.
In laboratory studies, insulin has been shown to stimulate the growth of breast cells. And, being overweight or obese has been identified as a risk factor for breast cancer, according to the American Cancer Society.
"These data suggest that hyperinsulinemia [excess insulin in the blood] is an independent risk factor for breast cancer and may have a substantial role in explaining the obesity-breast cancer relationship," the researchers wrote.
More information
The American Cancer Society has more on breast cancer risk factors.
