23andMe to offer BRCA genetic testing, but should I take this test?

March 08, 2018

23andMe, the prominent direct-to-consumer (DTC) genetic testing company, recently received FDA approval to offer a limited form of BRCA gene testing as part of the genetic testing products that they offer to consumers. BRCA1 and BRCA2 are the two genes most commonly linked to hereditary breast and ovarian cancers. Women who carry a mutation in one of these genes face fairly significant risks for developing breast and ovarian cancers.  High-risk screening and risk reducing strategies are strongly recommended for women who carry BRCA mutations, strategies which can literally save a woman’s life.

Testing is relatively inexpensive and only requires a saliva sample that is sent directly to the company.  It almost seems like a no-brainer to take the test.  So shouldn’t all women take up 23andMe’s offer of testing?

As the saying goes, if it sounds too good to be true, it probably is. First off, everyone carries BRCA1 and BRCA2 genes that we inherit from our parents.  Only someone who has inherited a mutated form of a BRCA gene faces the increased cancer risks. The problem is that each gene can mutate more than a thousand different ways; the 23andMe test only screens for 3 of those several thousand mutations!  Those 3 mutations are somewhat common among people who are Ashkenazi Jewish (about 2% of whom carry one of these 3 mutations). However, for non-Ashkenazi women and men, the test would miss more than 99% of all BRCA mutations. 

Secondly, about a dozen different genes have been linked to hereditary breast cancer. The 23andMe product does not screen for any of these other genes. Thus, even for Ashkenazi women, a normal result on the 23andMe product can offer only very limited reassurance.

Thirdly, 23andMe recommends that any positive genetic result be independently confirmed by a lab that specializes in hereditary cancer testing. Which would also make one think that maybe they would want to have a normal result verified as well.

Deciding about whether to undergo genetic testing is a very complicated process. Some questions to think about might be: How will a positive or a negative result affect my health care?  Is it better to undergo testing when I am 25 or when I am 55? What do the results mean for me specifically, as well as for my family? Am I emotionally ready to hear these test results, and am I willing to act on medical recommendations? What are my cancer risks if my test results are normal? Will a positive test result affect my ability to get health, life, or other forms of insurance? Is the BRCA test the best choice for me, given my medical and family history? If I have already had cancer, will testing be of any benefit?

The Swedish Cancer Institute offers genetic counseling to all women and men who are considering genetic testing for hereditary cancer through its Hereditary Cancer Clinic with services at the First Hill, Ballard, Edmonds, and Issaquah campuses. Our licensed and certified genetic counseling staff will meet with patients one-on-one to help them decide if genetic testing is appropriate, work with their care providers to help integrate test results into their medical care, help arrange genetic testing, and work with labs to verify insurance coverage. 

If you think you might be interested in learning more about genetic testing for hereditary forms of breast and other cancers, make an appointment with one of our genetic counselors by calling 206-215-4377.

Topics: Cancer