It is important to understand the difference between germline genetic testing and tumor biomarker testing. Germline genetic testing looks for inherited mutations in genes that are present in all the cells of your body. In contrast, tumor biomarker testing focuses on characteristics or genetic alterations found only in the cancer cells themselves.
Types of genetic mutations
BRCA1 and BRCA2 are genes that help normal cell growth and repair damaged DNA. Everyone has these genes, but some people are born with a genetic alteration that changes the way these genes work and increases the risk of developing certain cancers, including metastatic breast cancer (MBC).
Women who inherit a BRCA1 or BRCA2 mutation have a higher risk of developing breast cancer, often at a younger age, and are more likely to develop cancer in both breasts. Alterations to other inherited genes—such as CDH1, PALB2, PTEN, STK11, and TP53—have also been found to increase the risk of developing breast cancer. This is not a complete list, and research continues to identify additional gene changes that can influence cancer risk and treatment decisions.
Why should I consider taking a genetic test?
The results of a genetic test can help your doctor plan your breast cancer treatment—for instance, they may recommend targeted therapy that focuses on cancer-causing genes. But a genetic test can also reveal information that may be extremely helpful to your family members.
If you have an inherited BRCA alteration, you have a 50% chance of passing it on to your children, and there is a 50% chance your siblings have the alteration. Therefore, the results of your genetic test can impact medical decisions and options for you and your family.
Telling your loved ones about your genetic test results and potential risk for cancer
Sharing genetic test results with your family isn’t easy. Your test results may raise concerns among family members about their own cancer risk and medical decisions. It’s important to remember that a genetic test does not diagnose cancer itself. Rather, it shows whether you have a higher risk of developing certain cancers.
Genetic counseling can help your family members understand their own risk and make informed decisions about screening or preventive care. If they test positive for a gene alteration, there are options to detect cancer early or take steps to reduce their risk. If they test negative, they will know they are not at increased hereditary risk.
Learn more about genetic testing
- How do I get genetic testing? (FORCE: Facing Our Risk of Cancer Empowered)
- Which genetic test is right for me? (FORCE: Facing Our Risk of Cancer Empowered)
- What do my test results mean? (FORCE: Facing Our Risk of Cancer Empowered)
- Genetic vs genomic testing: What’s the difference in metastatic breast cancer? (Living Beyond Breast Cancer)
- BRCA testing and counseling (Sharsheret)
