New Research: Preventative Mastectomies and Reducing Breast Cancer Risk 

New research from Canada shows that preventive mastectomies can reduce the risks of breast cancer in women with certain forms of BRCA genes that, without intervention, significantly increase the risk of breast cancer.

Mutations Raise Risk

Every human has both the BRCA1 and BRCA2 genes. However, sometimes these genes become damaged or change in some way, resulting in a mutation that raises the risk of breast cancer. In fact, BRCA stands for Breast Cancer Gene, thus named because a mutation in the  BRCA1 and BRCA2 genes has been correlated with a higher risk of developing breast cancer. 

Previous studies have shown that certain variants of BRCA1 or BRCA2 increase a woman’s lifetime odds of breast cancer by 80%. Other studies have shown that mastectomies, the removal of breast tissue, reduce the risk of developing the disease by 90% in women with these gene variants. 

Several high profile celebrities underwent single or double mastectomies both before or after being diagnosed with breast cancer, notably Angeline Jolie, who underwent a preventative double mastectomy in 2013.

Jolie discovered that she had a mutation in her BRCA1 gene after her mother died of cancer, and that her risks of developing breast/ovarian cancer were very high. She made the decision to undergo a preventative double mastectomy and wrote a New York Times op-ed about it. She wrote, “But I am writing about it now because I hope that other women can benefit from my experience.”

New Research Explores Preventative Mastectomies

A new, long-term study conducted by lead author Kelly Metcalfe, of the University of Toronto, followed 1,600 women from nine countries. Every woman had BRCA gene mutations associated with increased breast cancer risks, and half of the women in the group underwent preventative mastectomies while the others did not. 

After six years, there were 20 cases of breast cancer and two deaths in the group of women who underwent the surgeries. In the group of women who did not opt for surgery, there were 100 breast cancer cases and seven deaths. 

The researchers from the University of Toronto concluded that preventative mastectomies reduce the risk of developing breast cancer in women with specific BRCA mutations by 80%. They also calculated that the odds of dying from breast cancer 15 years after the mastectomy was 1%.

The Importance of Genetic Testing for Early Breast Cancer Detection

According to the National Breast Cancer Foundation, 55–65% of women with the BRCA1 mutation develop breast cancer before age 70, and about 45% of women with the BRCA2 mutation develop breast cancer by age 70.

Early detection, however, can significantly increase the chances for successful treatment. This is where genetic testing comes in. A person who discovers that they have a BRCA mutation can consider possible measures to help reduce their risk of developing breast cancer in the future.

According to, not everyone needs genetic testing for BRCA mutations, as these mutations are fairly rare, presenting in about one out of 500 women.

However, because this mutation is a significant indicator of increased breast cancer risk, doctors may recommend testing to anyone with a family history of breast cancer or other cancers. As 5-10% of breast cancer cases are hereditary, genetic testing is important for any child whose parents have a BRCA mutation. 

Other high risk breast cancer indicators that may warrant genetic testing include:

  • If you’ve been diagnosed with breast cancer at a younger age
  • If more than one family member has been diagnosed with breast cancer
  • If you’re of Ashkenazi Jewish descent 

Women who are concerned about their risk should speak to their doctors immediately. 

The Decision to Undergo a Preventative Mastectomy

The decision to undergo breast removal as a preventative cancer measure isn’t easy for many women, despite the numbers showing that this procedure statistically reduces the risk of breast cancer.

Metcalfe noted that in Canada, 30% of women with BRCA1 or BRCA2 gene variants choose preventative mastectomies. However, she also believes that further research is needed in this area, as the more knowledge doctors can provide women with these genes, the more informed their decisions can be.