Undergoing a prophylactic bilateral mastectomy, the preventive removal of both breasts, significantly reduces the chances of developing breast cancer in women who carry gene mutations that put them at very high risk for the disease, according to a new Dutch study. The Dutch study confirms an earlier study conducted by Mayo Clinic researchers which also found that prophylactic mastectomy greatly reduces breast cancer risk. However, longer follow-up is needed to determine whether the decreased breast cancer risk remains throughout a woman’s lifetime.
The latest study involved 139 healthy women who had been found to have a mutation of the BRCA1 (breast cancer gene 1) or BRCA2 (breast cancer gene 2) gene. The National Cancer Institute estimates that women who carry mutations of BRCA1 and BRCA2 have a 50% to 85% chance of developing breast cancer compared to an average risk of 12% for all women. Genetic mutations account for approximately 5% to 10% of breast cancer cases and also increase the risk of ovarian cancer. Genetic testing is available for women who have a strong family history of breast cancer and want to know whether they carry mutated BRCA genes that substantially increase the risk of getting breast cancer.
At the time of enrollment into the study, none of the women had a personal history of breast cancer. Seventy-six of the women in the study decided to eventually undergo a prophylactic mastectomy while the remaining 63 women were closely monitored by physicians with clinical breast exams and either mammography or magnetic resonance imaging (MRI). After an average follow-up of three years, none of the women who had their breasts removed developed breast cancer. However, 8 of the 63 (12%) women who did not have prophylactic mastectomies got breast cancer, and one woman died from the disease.
This study shows that prophylactic mastectomy can be nearly 100% effective at preventing breast cancer, said Dr. Jan Klijn, chairman of the Rotterdam Family Cancer Clinic in The Netherlands, adding that women who have the surgery do not need to lose sleep over their fear of developing breast cancer. Breast reconstruction is usually possible after a prophylactic mastectomy.
However, other experts worry that because the study only followed the women for a short amount of time, that the results may not hold true as time passes. A few of the women may develop breast cancer later in life, said Dr. Martin Schwalb, director of the Center for Human and Molecular Genetics at the University of Medicine and Dentistry in New Jersey. Also, the majority of the women who underwent prophylactic mastectomy in the study also had their ovaries removed (prophylactic oophorectomy), a preventive procedure that has also been shown to reduce breast cancer risk.
Nevertheless, experts call the Dutch study the strongest to date that shows that prophylactic mastectomy can significantly reduce the chances of developing breast cancer. A 1999 study conducted by Mayo Clinic researchers from Rochester, Minnesota had found that having the breasts removed reduced the risk of breast cancer by 90%. However, the Mayo Clinic study was "retrospective," meaning that the researchers collected their data after the women had already had the surgery. By contrast, the Dutch study was "prospective," meaning that the researchers were able to make sure that all of the women in the study received the same treatment (either prophylactic mastectomy or breast cancer screening tests).
Yet physicians warn that prophylactic mastectomy is still not appropriate for all women at high risk of breast cancer. While testing positive for BRCA gene mutations significantly increases the risk of developing breast cancer, some of these women will never develop the disease. Surgical complications can also occur with prophylactic mastectomy. An estimated 30% of women who have the surgery experience complications, such as fluid trapped in the wound (seroma), and half of those 30% need additional surgery. Yet perhaps the most difficult aspect of the procedure is its effect—a woman is left without her breasts. While breast reconstruction, prostheses (breast forms), and other options are available after prophylactic mastectomy, not all women wish to deal with the physical and emotional aftermath of the surgery. For these women, other preventive options, such as the drug tamoxifen, are more suitable than having the breasts removed.
In the study, the women who did not have their breasts removed received a yearly mammogram or MRI of their breasts, physician-performed clinical breast exams every six months, and monthly breast self-exams. In an accompanying editorial in The New England Journal of Medicine, Dr. Andrea Eisen and Dr. Barbara Weber suggest that taking the drug tamoxifen and having the ovaries removed (oophorectomy) is a viable alternative to help prevent breast cancer. Other options include routine breast cancer screening or participation in the STAR clinical trial which is comparing the effectiveness of tamoxifen to a similar drug, raloxifene (brand name, Evista) in helping to prevent breast cancer.
However, many women are not classified at very high risk of breast cancer and thus do not need to consider these options. For all women, routine breast cancer screening helps detect the disease in early stages when the chances for successful treatment and survival are the greatest.
Guidelines for early breast cancer detection:
- All women between 20 and 39 years of age should practice monthly breast self-exams and have physician performed clinical breast exams at least every three years.
- All women 40 years of age and older should have annual screening mammograms, practice monthly breast self-exams, and have yearly clinical breast exams. The clinical breast exam should be conducted close to and preferably before the scheduled mammogram.
- Younger women with a family or personal history of breast cancer should talk to their physicians about beginning annual mammograms before age 40.
- The study, "Breast Cancer After Prophylactic Bilateral Mastectomy in Women with a BRCA1 or BRCA2 Mutation," is published in the July 19, 2001 issue of The New England Journal of Medicine. An abstract of the study is available at http://content.nejm.org/
- The July 18, 2001 MSNBC.com report, "Breast Removal Prevents Cancer, Study Confirms," is available at http://www.msnbc.com/news/602102.asp
- The July 18, 2001 Associated Press report, "Preventive Mastectomies May Save Lives," is published on CNN.com, http://www.cnn.com/
- To learn more about prophylactic mastectomy, please visit http://www.imaginis.com/breasthealth/prophylactic_mastectomy.asp
- To learn more about preventive options for breast cancer, please visit http://www.imaginis.com/breasthealth/preventive.asp
- To learn more about BRCA1 (breast cancer gene 1), BRCA2 (breast cancer gene 2) or other genetic risks for breast cancer, please visit http://www.imaginis.com/breasthealth/genetic_risks.asp
- To learn more about candidates for genetic testing, please visit http://www.imaginis.com/breasthealth/BRCA.asp
