Genetics and Breast Cancer

Most women who have breast cancer in their families will never get breast cancer themselves—even if a mother or sister has died of breast cancer. In fact, even a woman with the mutated gene for breast cancer may never get breast cancer, even though her risk is much greater than other women with "breast cancer in their families" who don't have the mutated gene.

A family history of breast cancer increases your risk of breast cancer, but it is not necessary to choose more aggressive treatment or more radical surgery just because you have a family member with breast cancer. Research shows that a strong family history of breast cancer does not affect local recurrence rates or overall survival among women who undergo breast-conserving surgery. So family history should not influence your choice of either mastectomy or breast-conserving surgery.

Women diagnosed with breast cancer who have a family history of breast cancer are at increased risk of getting breast cancer in their healthy breast. Sometimes these women decide to have the other removed to prevent cancer in the future. Occasionally, women with several close relatives with breast cancer decide to have both their breasts removed as a preventive measure, even if they have never been diagnosed with breast cancer. Removing one or two healthy breasts reduces the risk of future breast cancer, but it does not eliminate the risk completely. The disadvantage is that the surgery will be unnecessary for most women who choose it, because most women who have a breast removed as a preventive measure would never have gotten breast cancer even if the breast (or breasts) were not removed.

Instead of surgery, there are other strategies that can prevent breast cancer, and it is advisable to obtain a second professional opinion before deciding to undergo a mastectomy to prevent, rather than treat, breast cancer.