A new study from the Abramson Cancer Center at the University of Pennsylvania, published in the Journal of Clinical Oncology (JCO), shows that bilateral prophylactic mastectomy can reduce breast cancer risk by more than 90% in women with BRCA1 and BRCA2 genetic mutations, and may be even more effective when performed concurrently with or following oophorectomy (removal of the ovaries).
The study, which calculated the risk reduction from bilateral mastectomy in BRCA1 and BRCA2 mutation carriers, evaluated 483 women from 11 sites in the United States, Canada, United Kingdom and the Netherlands over six years.
Breast cancer was diagnosed in two of the 105 women (1.9%) who had bilateral prophylactic mastectomy, compared to 184 of the 378 (48.7%) who did not undergo the procedure. Mastectomy reduced breast cancer risk by approximately 95% among women with prior or concurrent prophylactic oophorectomy, and by 90% among women with intact ovaries.
"Our study shows that bilateral prophylactic mastectomy markedly reduces the risk of breast cancer in women who are genetically predisposed to the disease," said Dr. Barbara Weber, MD, Professor of Medicine and Genetics at the University of Pennsylvania, an investigator in the Abramson Family Cancer Research Institute, and senior author of both studies. "Women undergoing this procedure should feel confident that if they choose this risk management option, it will reduce their risk of breast cancer to almost zero."
Weber noted that while bilateral mastectomy is optional for BRCA1 and BRCA2 mutation carriers, bilateral prophylactic oophorectomy at the completion of childbirth should be the standard of care for these at-risk women, since it has been shown to reduce risk of ovarian cancer by 95% and breast cancer by 50%.
"Undergoing prophylactic mastectomy is a very personal decision. Women who choose to have their breasts removed in addition to their ovaries should know that prophylactic mastectomy is an option that really works, and makes taking HRT after oophorectomy even safer," she added.
SOURCES:
Journal of Clinical Oncology, online edition, February 23, 2004
American Society of Clinical Oncology (http://www.asco.org)
