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Removing Healthy Breasts Reduces Breast Cancer Risk (dateline April 17, 2000)

Researchers have found that the preventive removal of both breasts ( prophylactic bilateral mastectomy) reduces breast cancer risk for women with a genetic predisposition to the disease. Up until now, physicians have not had reliable data that showed the effectiveness of prophylactic mastectomy. Though the decision to have the surgery should not necessarily be a woman’s first choice for preventing breast cancer, researchers say that prophylactic mastectomy appears to reduce breast cancer risk by 90% in women who have BRCA1 (breast cancer gene 1) or BRCA2 (breast cancer gene 2) mutations. Prophylactic mastectomies also seem to significantly lower the risk in women with a strong family history of breast cancer.

In the study, researchers retrospectively followed 214 women who had prophylactic bilateral mastectomies from 1960 to 1993. Of the 28 women in the study who were found to have BRCA1 or BRCA2 genetic mutations, none developed breast cancer (although one developed ovarian cancer ). The patients have been followed for an average of 14 to 15 years after the procedure, and the average age of the women when they had the mastectomies performed was 40.

Though the procedure can dramatically reduce the risk of breast cancer, surgically removing the breasts is not a guarantee that breast cancer will never develop. While a mastectomy removes the majority of breast tissue, it is impossible to remove every breast cell. According to Dr. Hartman, if only three cells are left, cancer could develop from those three cells. In the study, three of the 214 women developed breast cancer and two of the women died.

Women with BRCA gene mutations account for approximately 10% of breast cancer cases. If a woman carries a BRCA1 gene mutation, her risk of breast cancer is:

  • 20% by age 40
  • 51% by age 50
  • 87% by age 60

For high risk women who do not wish to have their breasts removed, physicians usually recommend annual mammograms and clinical breast exams to help detect breast cancer early when treatment is usually less invasive and the chances of survival are greater. All women 40 years of age and older are encouraged to have annual screening mammograms. Younger women who are at high risk for breast cancer (as determined by a physician) should ask their doctors about beginning screening mammograms at a younger age, as early as age 25 in some cases. The drug tamoxifen is also now being used in many high risk women to help prevent breast cancer.

While preventive breast removal may increase life expectancy in women with aggressive tumors, some women with BRCA1 or BRCA2 gene mutations never develop breast cancer and would obviously not benefit from a prophylactic mastectomy. Also, if breast cancer is detected early, less invasive procedures such as lumpectomies may be performed without having to remove the entire breast(s).