Metformin Could Help Prevent Some Breast Cancers
More studies are needed to better understand whether there is a cause-and-effect relationship between metformin and cancer or if the increased risk is due to a lack of protection from metformin, Sandler said.
The results were published on January 29 in the Annals of Oncology.
Metformin has been hailed as a miracle for many diseases other than diabetes. Some research has linked it to longer lifespan, reduced risk of vision loss, and improved fertility in both men and women.
The new study does not suggest that women without diabetes should take metformin to reduce the risk of breast cancer, said Dr Pamela Goodwin, co-author of an editorial accompanying the study. She is professor of medicine at the University of Toronto and former director of the Marvelle Koffler Breast Center at Mount Sinai Hospital in Toronto.
More research is needed to fully understand the link between diabetes and breast cancer and to clarify the role that metformin can play, Goodwin said.
Losing weight and participating in regular physical activity can help reduce the risk of diabetes, she said, adding that it could also have an impact on breast cancer risk.
“If you have type 2 diabetes, be treated properly and in many cases that means taking metformin. Also make sure you get regular mammograms,” Goodwin said.
Dr. Sarah Cate, director of the special monitoring and breast program at Blavatnik Family-Chelsea Medical Center at Mount Sinai in New York City, reviewed the results.
“Certainly, metformin helps with weight loss, which is linked to estrogen-induced breast cancers, so this may explain why fewer patients on metformin have contracted this type of breast cancer,” she said.
Cate and Goodwin noted that the results for triple negative breast cancer need to be fleshed out.
“The number of patients with triple negative breast cancer was small, so we cannot draw any conclusions that would change the practice,” Cate said.
Breastcancer.org offers more information on risk factors for breast cancer.
SOURCES: Dale Sandler, PhD, chief, Division of Epidemiology, US National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina; Pamela Goodwin, MD, MSc, professor, medicine, University of Toronto, and former director, Marvelle Koffler Breast Center, Mount Sinai Hospital, Toronto; Sarah Cate, MD, assistant professor, surgery, Icahn School of Medicine, Mount Sinai, New York, and director, special monitoring and breast program, Blavatnik Family-Chelsea Medical Center, Mount Sinai, New York City; Annals of Oncology, January 29, 2021
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