Study: Prophylactic Mastectomy Dramatically Lowers Breast Cancer Risk

Prophylactic mastectomy dramatically lowers the risk of breast cancer in women at the highest risk for developing the disease, according to researchers at the Mayo Clinic.

Removal of both breasts in women with the BRCA1 and BRCA2 gene mutations reduces the risk of subsequent breast cancer by 89.5 to 100 percent, according to the study published in the Journal of the National Cancer Institute.

Researchers followed 26 high-risk women who were known carriers of the two gene mutations. All of the women had surgery to remove both of their breasts. During the follow-up period, 13.4 years so far, none of the women has developed breast cancer.

"Calculations predict that six to nine breast cancers should have developed in this group of carriers without prophylactic surgery," said Dr. Lynn Hartmann, oncologist and lead researcher of the study. "That translates into a risk reduction of 89.5 to 100 percent for bilateral prophylactic mastectomy."

A prior Mayo study showed that prophylactic mastectomy reduced the risk of subsequent breast cancer by approximately 90 percent in women with a strong family history of the disease. A group of 214 women at high risk who had both breasts removed was compared with sisters who had not had the surgery.

The current study complements a Dutch study showing similar risk reduction in a larger number of carriers of the two gene mutations who had double prophylactic mastectomy. That study had a shorter period of follow up than the current Mayo study.

Other Sources: Mayo Clinic