Diabetes Treatment May Lower Breast Cancer Risk

Diabetes treatments may reduce a risk factor for breast cancer.

In a study of 5,644 women participating in the Danish Diet, Cancer, and Health study group, researchers found that medications and lifestyle changes to treat type 2 diabetes, such as metformin and even dietary changes, reduces breast density.

Breast density is one of the strongest risk factors for breast cancer. In fact, women with more than 75 percent dense breast tissue have a four to six times greater risk than women with more fatty tissue. Dense tissue can also make breasts more difficult to image with a mammogram. [PROVE].

The team, led by Zorana Jovanovic Andersen, [DEGREE], Associate Professor of Epidemiology, at the University of Southern Denmark, Esjberg, Denmark, looked at medical data for women who had mammograms between 1993 and 2001. The mean average was 56 years, 4,500 were post-menopausal, and 137 (2.4 percent) had diabetes. In addition, 3,180 (56.3 percent) had breasts with mixed or dense tissue.

Of those women with diabetes, 44 women who controlled their diabetes with diet alone had less dense or mixed breast tissue, compared with fatty tissue.

Another 62 women, who took oral medications for diabetes, also had less breast density. Women who used insulin, however, had increased odds of having mixed or dense breasts. The results were not affected by menopausal status or body mass index. The team presented their findings in a spotlight poster presentation on March 9, at the 10th European Breast Cancer Conference (EBCC-10).

"Women with diabetes were less likely to have mixed or dense breasts, as opposed to fatty ones, both before and after adjustment for other factors such as being overweight," Andersen said. However, the researchers also emphasized that the finding that insulin use is associated with increased breast density should not imply an increased breast cancer risk. "Breast density is only one of many risk factors for developing breast cancer," she noted.

“This study shows clearly that a link between diabetes treatment and breast density, an important risk factor for the disease, has been made. I hope that these findings will lead to further research into the effect of cheap, easily-available drugs such as metformin, not just on breast density, but on breast cancer risk overall,” said Professor Fatima Cardoso, Conference Chair and Director of the Breast Unit of the Champalimaud Clinical Centre in Lisbon, Portugal.