While most breast cancers are “sporadic,” that is to say, not associated with a person’s family history or genes, some people may have mistakes or “mutations” in certain genes that are designed to prevent us from getting cancer. These mutations, therefore, increase the risk of developing cancer.
Your doctor will ask you about people in your family who may have had cancer. This information will help determine the risk you have of carrying such a mutation. If your history includes any of the following, your doctor may then recommend genetic counseling (talking to someone about your genetic risk) and maybe even genetic testing (a test done to see if you carry a mutation):
- You, or someone in your family, have been diagnosed with breast cancer before the age of 45.
- You have been diagnosed with 2 breast cancers (either in the same breast or one in each breast).
- You are a male who has developed breast cancer.
- You, or someone in your family, have been diagnosed with ovarian cancer (especially if not mucinous).
- You are of Ashkenazi Jewish heritage and either you, or someone in your family, have been diagnosed with breast cancer.
- A BRCA1 or BRCA2 gene mutation has been identified in your family.
- You have been diagnosed with “triple negative” breast cancer before the age of 60.
- You have been diagnosed with pancreatic cancer and have a family history of breast and/or ovarian cancer.
Your doctor or genetic counselor will discuss with you the process of testing and the implications on insurance, as well as the potential results and what they mean. You should be sure to ask any questions you have.
The most common genes in which mutations are associated with breast cancer are BRCA1 and BRCA2. BRCA gene mutations occur in approximately 1 in 400 to 800 people. If you have a mutation in 1 of these genes, you face a higher lifetime risk of developing breast cancer (approximately 80%), cancer in the other breast (approximately 30% at 10 years), ovarian cancer (approximately 40% for BRCA1 and approximately 20% for BRCA2), and other cancers as well. In addition to BRCA1 and BRCA2, your doctor or genetic counselor may recommend testing for other gene mutations that may also predispose you to developing breast cancer.
If you test positive for a genetic mutation, there are things that you can do to reduce your risk of developing cancer. Prophylactic mastectomies (removing the breast tissue) can reduce your breast cancer risk by 95% to 97%. If you are premenopausal, removing your ovaries may reduce your risk of breast cancer by more than 50%, while also reducing your risk of developing ovarian cancer. If you test positive for a genetic mutation but opt not to remove your breasts, you should have annual screening with breast MRI.