Lead researcher Lynn Hartmann, MD, of the Mayo Clinic in Rochester, Minn., reported these findings at the annual meeting of the American Association for Cancer Research that took place recently in San Francisco.

The BRCA genes are tumor suppressor genes that help prevent cancer when they are functioning normally. Inherited mutations in these genes give women a 60-70 percent chance of developing breast cancer by age 70. Some women with BRCA gene mutations choose to have both breasts removed to lower their risk of developing the disease.

"This study is reassuring to women who chose that method to protect themselves from the very high risk of breast cancer they inherited with the altered BRCA genes," says Debbie Saslow, PhD, director of breast and cervical cancer for the American Cancer Society (ACS). "But it may not be the preferred choice – or the best choice – for every woman at increased risk because of BRCA mutations or other risk factors. Other options for these women include earlier and more frequent screening, and tamoxifen, though tamoxifen can only be taken for five years."

An earlier study by the same researchers showed the breast removal surgery – called prophylactic bilateral mastectomy – to be an effective, though drastic, way to reduce risk in women likely to develop breast cancer. The possibility of developing breast cancer once breasts have been removed is much smaller but still exists because not all breast tissue can be removed.

The original study, published in The New England Journal of Medicine (Vol. 340, No. 77), followed 214 women at high risk of breast cancer for a median of 15 years. These women, who have family histories of breast cancer, elected to have both breasts removed to lower their chances of developing the disease. The surgery reduced their breast cancer risk by about 90 percent, with only three breast cancer cases developing among the 214 women, compared to the 38 that would have been expected in such a high-risk group.

That earlier study involved high-risk women but did not factor in whether women had BRCA mutations because the surgeries were performed before testing for the BRCA genes was available.

In the new follow-up study, Dr. Hartmann and her colleagues are looking at the number of breast cancer cases among the 214 study participants. Of the 148 women from the group who have thus far been tested for BRCA1 and BRCA2 mutations, 28 have tested positive, though none have developed breast cancer since they had their surgeries.

Women who are at increased risk for breast cancer because of a family history of the disease should seek advice from a licensed, qualified genetic counselor, so they may gather all the facts they need to make a truly informed decision, Dr. Saslow says.

She encourages women interested in being tested for BRCA mutations to consider contacting the National Society for Genetic Counselors to obtain information on genetic testing. Information is also available by calling the Society’s toll-free information line at 1-800-ACS-2345.

• Genetic Testing - Patient Privacy and Discrimination Considerations
• National Society for Genetic Counselors