Prophylactic Mastectomy A recent study published in The New England Journal of Medicine by Hartmann et al from the Mayo Clinic reported that prophylactic mastectomy can significantly reduce the incidence of breast cancer in high risk women. The study triggered a flurry of responses: The Chicago Tribune printed an editorial entitled, “Preventative Mastectomy, Happy Acceptance of a Horrific Procedure,” which was followed by a response from Joseph Imperato, M.D. titled, “Offering Hope to Cancer Patients.” The retrospective study, entitled “Efficacy of Bilateral Prophylactic Mastectomy in Women with a Family History of Breast Cancer,” provides important information for high-risk women concerned with reducing their chances of being diagnosed with breast cancer. Women who underwent bilateral prophylactic mastectomies at the Mayo Clinic between 1960 and 1993 were divided into two groups; high risk and moderate risk. The 214 women identified as high risk had one or more relatives with breast cancer, early age at diagnosis of cancer, family history of ovarian cancer, bilateral breast cancer, or breast cancer in male family members. Of the 425 women considered at moderate risk, 268 had at least one affected first-degree relative, 46 had two aunts, cousins or both, and 111 had family histories of breast cancer involving fewer second or third-degree relatives. The study used the Gail model (a statistical model used to calculate a woman’s risk of getting breast cancer) to determine the expected number of breast cancers in the moderate risk group. The model predicted that approximately 37 women would develop breast cancer. Only 4 breast cancers occurred. This represents an 89.5 percent reduction in risk. To determine the expected number of breast cancers in the high risk group, the researchers compared them to their sisters who had not undergone prophylactic mastectomy. The results showed 156 (38.7 percent) of the sisters were diagnosed with breast cancer, while only 3 (1.4 percent) of the high risk group who had prophylactic mastectomies developed breast cancer. These results were the basis of the conclusion that prophylactic mastectomy is associated with a 90% reduction in the risk of developing breast cancer for women at high risk. Some limitations of the study should be considered, however, when weighing the reported findings. Women with different risk factors were put into the same groups. The study did not identify who had BRCA1 or BRCA2 mutations, for example. An analysis of these genetic mutations might have given more specific information about exactly which women might benefit from the procedure. Ethnic background was not evaluated either. Other limitations stem from how the data was analyzed. There are still very few clear cut answers about most aspects of breast cancer and there are no simple choices. Women must take many factors into consideration when determining which route to take. They should consider the objective risk of developing breast cancer, their breast density (on mammogram), the ease of conducting a breast self-exam or clinical breast exam, their personal values and experiences (particularly with other family members with breast cancer), experiences with the medical system, career and family responsibilities, and perhaps most importantly, their own emotional reaction. High risk women have several options for reducing their chances of developing breast cancer, including being closely monitored by a breast specialist, taking Tamoxifen, or chosing prophylactic mastectomy. All contain both risks and benefits. No choice is guaranteed. As each individual is ultimately responsible for making decisions, information is the best defense. Many women tend to over-estimate their personal risk of breast cancer, yet many would not consider this option. For those who have considered it, this study may help in making a decision. In the Spring Issue of this newsletter we noted that researchers are constructing a repository of information on this subject and would like to know more about women who have had one or both breasts removed prophylactically. If you have undergone this procedure and would like to become involved with these studies, please call the BABCN office at 408-261-1425.
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