Results from a new study have shown that women with type 2 diabetes are at a higher risk of developing breast cancer. However, it appears that taking the medication metformin, used in the treatment of diabetes, reduces the risk of the most common type of breast cancer.
Compared to women without diabetes, the risk of developing estrogen-positive breast cancer was reduced by 38% among women with type 2 diabetes who had used metformin for 10 years or more. The study also found that metformin does not protect against estrogen receptor-negative breast cancer and may increase the risk of triple-negative breast cancer as well. The lead author of the study, Dr. Dale Sandler, head of the epidemiology branch at the National Institute of Environmental Health Sciences, stated, "Women with type 2 diabetes and their doctors should consider whether the diagnosis and treatment of type 2 diabetes should influence the frequency of their breast cancer screenings."
In fact, metformin lowers blood sugar levels in diabetic patients by reducing the amount of glucose produced in the liver. However, how this medication may protect women with diabetes from breast cancer is not entirely clear yet. Dr. Sandler noted, "Metformin may improve insulin sensitivity and correct elevated insulin levels in the blood by reducing the amount of insulin and insulin-like growth factor circulating in the body, which may inhibit cancer-related cell signaling." He also added that metformin may slow the growth of breast cancer by activating an enzyme called AMP-activated protein kinase (AMPK), which blocks a pathway involved in the spread of cancer cells, and that it may inhibit estrogen receptors that play a role in the growth and progression of breast cancer to more severe and aggressive forms.
It is worth noting that this new study included more than 44,000 women who were followed for over eight years, with ages ranging from 35 to 74. Although they had not been diagnosed with breast cancer at the start of the study, they were sisters or half-sisters of women with breast cancer. Participants completed questionnaires every three years. The study found that while women with type 2 diabetes who took metformin were protected from estrogen-positive breast cancer, they were also at a 74% higher risk of developing triple-negative breast cancer. They noted that a small group of participants had developed this type of breast cancer, so it is premature to draw any conclusions regarding this matter.
Additionally, Dr. Sandler stated that further research is needed to determine if there is a causal link between metformin use and breast cancer. It is worth mentioning that metformin has been welcomed by many researchers and experts as a miracle drug for several conditions beyond diabetes, with some studies linking it to increased lifespan, reduced risk of vision loss, and improved fertility in both men and women.
