Could Insulin Increase Breast Cancer Risk?

Women on insulin might need extra breast cancer screening
Women on insulin might need extra breast cancer screening

HealthDay News — Women with diabetes who take insulin appear to have a higher incidence of dense breasts, a known risk factor for breast cancer, according to research scheduled for presentation at the European Breast Cancer Conference, held from March 9 to 11 in Amsterdam.

Zorana Andersen, PhD, an associate professor of epidemiology at the University of Southern Denmark in Esjberg, and colleagues evaluated 5,644 women, all of whom had mammograms between 1993 and 2001. The average age was 56. Most of the women were past menopause. More than half had breasts classified as mixed or dense. Slightly more than 2 percent of the women had diabetes.

Overall, women with diabetes were less likely to have mixed or dense breasts, the researchers found. However, women receiving insulin injections were more than twice as likely to have dense or mixed breasts. This was true regardless of their body mass index, or whether they had gone through menopause, the researchers said. Meanwhile, women with diabetes who managed their condition with diet or with non-insulin medications were less likely to have dense breasts.

"Insulin is a growth promoting factor of all body tissues," Andersen told HealthDay, "and thus it is plausible that it can increase the amount of epithelial or stromal tissue in the breast, thus increasing overall breast density." For now, Andersen said, women should be aware that different types of diabetes treatments seem to affect breast density differently.

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