Does family history matter if I have a negative breast cancer genetic test? The answer to this question depends on who else in your family has been tested for a genetic mutation. The majority of breast cancers occur sporadically, meaning that no genetic mutation is responsible for that cancer. However, approximately 10% of breast cancers are thought to be hereditary, or due to specific genetic mutations passed down through generations of family members. (Unfortunately all of the genetic mutations that are responsible for breast cancer have not yet been identified.)

If there is suspicion that within your family there is a genetic abnormality that is responsible for breast cancer, it is ideal for your family members who have been diagnosed with breast cancer to be tested. If any of these relatives are found to have a specific genetic mutation that causes breast cancer, all other family members can then be tested for that mutation. Keep in mind that if a family member tests positive for a specific mutation but your genetic test is negative, then you do not carry the specific genetic mutation responsible for breast cancer in your family. These results mean that are you not considered at high risk for developing breast cancer due to the specific genetic mutation. In addition, because you cannot pass down a genetic mutation you do not have, your children will not need to be tested for the specific mutation.

If your family members who have had breast cancer cannot be tested for a genetic mutation, then your family history does matter since your doctor cannot be sure what caused the breast cancer in these relatives. You will still be considered at high risk for developing breast cancer even if your genetic test results are negative; however, your risk will not be as high as if you were found to have a genetic abnormality. Your physician can calculate your estimated lifetime risk of developing breast cancer and recommend appropriate screening based on this risk assessment.