I had many questions posed to me as of late about the role of genetics - more importantly genetic testing/counseling - in reference to breast cancer. It really is difficult to explain to the average person who knows very little about breast cancer. I made a promise to someone - the promise was to post more in-depth info on genetic testing and breast cancer…so here it goes.
Genetic testing provides individuals the opportunity to determine if their family history of breast cancer may be due to a BRCA1 or BRCA2 mutation. Because the mutations greatly increase risk, having the knowledge of one’s genetic status can allow an individual to take certain steps to try to prevent the onset of breast cancer or to diagnose and treat it in early stages when it is most curable.
Although the tests for the BRCA1 and 2 mutations require only a blood sample, there are many risks and benefits that should be weighed in depth before an individual goes through with the testing. Because of the potential physical, emotional and financial impact of knowing one’s genetic status, testing for the BRCA mutation is recommended only for families with a strong history of breast cancer.
Typically, testing is first done on an immediate family member who has been diagnosed with breast cancer. If no BRCA mutation is found in the family member, this means the rest of the family members would also be free of the mutation, which saves them the trouble, concern and cost of going through testing. If a mutation is found, however, this means the other family members can be quickly and efficiently tested for the specific BRCA mutation that was discovered.
While the BRCA mutations are by far the most common inherited mutations linked to an increased risk of breast cancer, there are other known inherited mutations that also increase the risk of the disease, including those in the genes p53, ATM, CHK2 and PTEN/ MMAC1. Testing exists for some of these mutations, but is not often done because the mutations are much more rare than those in BRCA 1 and 2.
A woman’s lifetime chance of developing breast and/or ovarian cancer is greatly increased if she inherits an altered BRCA1 or BRCA2 gene. Women with an inherited alteration in one of these genes have an increased risk of developing these cancers at a young age (before menopause), and often have multiple close family members with the disease. You can read even more detailed information about what happens after genetic testing, what may occur with a positive result, as well as numerous psychological implications in the National Cancer Institute’s website.