Genetic Testing
The terms “genomic testing” and “genetic testing” are both used frequently in breast cancer discussions. They are often used interchangeably, but they actually have different goals and outcomes. Genomics usually refers to testing on the tumor itself, while genetics usually relates to testing of the patient’s normal blood cells or saliva. Genetic testing helps determine whether you have inherited a mutation (called a germline genetic mutation) that increases your risk for developing certain types of cancer — even if you have not been diagnosed with cancer.
Several types of cancer, including breast cancer, are known to run in families. Determining whether you have hereditary breast cancer is important because an inherited abnormality in the BReast CAncer 1 (BRCA1) or Breast CAncer 2 (BRCA2 ) gene carries with it an increased likelihood of developing breast cancer and/or ovarian cancer.
Every individual has BRCA genes. When they are normal, these genes prevent tumor growth, fix damaged cells and help cells grow normally. When they have mutations, they increase your risk for cancer. The BRCA1 and BRCA2 genes are the most commonly inherited mutated genes known to cause breast cancer. Your doctor will test for these and may test for others.
If you have a family history of a particular type of cancer, you may consider genetic testing to find out whether you carry the corresponding gene. The presence of inherited mutations in the BRCA1 and BRCA2 genes or other cancer-susceptibility genes may influence your decisions regarding drugs for cancer prevention, prophylactic surgery to remove the breasts and/or ovaries, and different systemic treatments, such as PARP inhibitors.
However, if you have not already been diagnosed with breast cancer but discover you have inherited a mutated gene, it does not mean you will automatically develop cancer; it only means the risk is increased and you can explore ways to lower it, such as surgery, medication, frequent screenings or lifestyle changes.
Keep in mind that frequent screenings for patients with inherited mutations do not prevent breast cancer but enable very early detection when it is highly curable.
The following risk factors may indicate that you have inherited an abnormal gene:
- Family history of cancer
- Cancer at an early age
- Multiple cancers in one relative
- Rare cancers
- Certain ancestry, such as Ashkenazi Jewish heritage
- Certain types of breast cancer, such as triple negative breast cancer (TNBC)
