Does Metformin Reduce Risk for Breast Cancer?

Patients with diabetes who received metformin had a lower risk for breast cancer than patients without diabetes.

Accumulating evidence suggests that metformin, a drug commonly used to treat patients with type 2 diabetes, might reduce the risk for developing breast cancer. Now, investigators have examined this possibility in postmenopausal women who participated in the Women's Health Initiative (WHI) trials.

The cohort of 68,019 women included 3401 patients with type 2 diabetes at study entry and excluded patients with type 1 diabetes. During a mean follow-up of 11.8 years, an additional 7889 received a diagnosis of diabetes, and 3273 received a diagnosis of invasive breast cancer.

Patients with diabetes who received medications other than metformin had a slightly higher risk for breast cancer than patients without diabetes (hazard ratio, 1.16; 95% confi…

Reviewing Author

William J. Gradishar, MD

Disclosures

Consultant/Advisory BoardLilly; AstraZeneca; Gilead

Grant/Research SupportBreast Cancer Research Foundation

Editorial BoardsClinical Breast Cancer; Oncology; Annals of Surgery; Breast Cancer Research and Treatment

Leadership Positions in Professional SocietiesNational Comprehensive Cancer Network (Chair, Breast Cancer Panel); American Board of Internal Medicine (Medical Oncology Board)