context: In hopes of avoiding future disease, some women at very high risk of developing breast cancer elect to have both breasts surgically removed, a procedure called bilateral prophylactic mastectomy or preventive mastectomy. The surgery aims to remove all breast tissue that potentially could develop breast cancer. A preventive mastectomy might also be considered if the woman has the BRCA1 or BRCA2 genetic mutation that increases her risk of developing breast cancer, a strong family history of breast cancer, a diagnosis of lobular carcinoma in situ ( LCIS), a family history of breast cancer, or history of radiation to the chest before age 30. A recent study suggests that prophylactic mastectomy may reduce the risk of breast cancer by up to 100% if there is a strong family history of breast cancer or a BRCA genetic mutation. However, risk reduction results vary widely for many reasons. In some studies, women had prophylactic mastectomies for non-high risk reasons, such as pain, fibrocystic breast disease, dense breast tissue, cancer phobia, or a family history of breast cancer. Approximately 10% of women will develop breast cancer, even though their breast tissue has been removed. But in most studies, patients did not develop breast cancer after prophylactic mastectomy. However, many of these patients would not have been considered high risk for developing cancer. Some experts have argued that even for high-risk women, prophylactic mastectomy is inappropriate, because not all breast tissue can be removed during a surgical procedure. In addition, the only groups undergoing prophylactic mastectomy that have been shown to possibly have a survival advantage (live longer) are pre-menopausal women with endocrine receptor-negative breast cancers and women with a BRCA genetic mutation. Breast cancers may develop in the glandular tissue of the breast, specifically in the milk ducts and the milk lobules. These ducts and lobules are located in all parts of the breast tissue, including tissue just under the skin. The breast tissue extends from the collarbone to the lower rib margin, and from the middle of the chest, around the side and under the arm. In a mastectomy, it is necessary to remove tissue from just beneath the skin down to the chest wall and around the borders of the chest. However, even with very thorough and delicate surgical techniques, it is impossible to remove every milk duct and lobule, given the extent of the breast tissue and the location of these glands beneath the skin. According to the National Cancer Institute, only those women who are at very high risk of breast cancer should consider preventive mastectomy. This includes women with one or more of the following risk factors: BRCA or certain other gene mutations Strong family history of breast cancer Previous cancer in one breast and high risk of developing breast cancer in the opposite breast History of lobular carcinoma in situ ( LCIS) plus family history of breast cancer History of radiation to the chest before age 30 Preventive mastectomy should only be considered after you've received the appropriate genetic and psychological counseling to discuss the psychosocial impacts of the procedure. For women who choose prophylactic mastectomy, several new and important surgical options have become available. It is now possible to remove breast tissue using skin-sparing techniques in which the underlying breast tissue is removed from just under the skin, down to the chest wall. This technique removes the vast majority of the glands where breast cancer may be likely to develop. The nipple and surrounding tissue, called the areola, are removed, because the ducts converge toward the nipple, creating a concentrated area of duct tissue. However, the skin of the breast is spared, preserving the breast skin envelope. When skin-sparing mastectomy is combined with immediate breast reconstruction, the results can be excellent. Many women who choose prophylactic mastectomy, often combined with immediate reconstruction, are very pleased, not only with their choice but also the reconstruction. While surgery is not an approach that should be advocated for all high-risk individuals, it can be very important for some women. It is important that you talk to your doctor to learn about all your options.