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. The surgery aims to remove all breast tissue that potentially could develop breast cancer. Preventive breast cancer surgery also may be considered if a woman has already had breast cancer and is therefore at increased risk for developing the disease again in either breast.

Is Prophylactic Mastectomy Effective?

A recent study suggests that prophylactic mastectomy may reduce the risk of breast cancer by as much as 90%. However, results vary widely. In some studies, women had prophylactic mastectomies for a variety of reasons, such as pain, fibrocystic breast disease, dense breast tissue, cancer phobia or a family history of breast cancer. Some women still developed breast cancer even though they had their breast tissue 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. To understand why, we need to know what comprises breast tissue and where cancer originates.

Where Does Cancer Form?

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 just beneath the skin.

VitaDocs Medical Reference provided in collaboration with the Cleveland Clinic