At-Home DNA Test for Breast Cancer Risk Has Limitations

The ability to conduct certain tests and screenings from home have become increasingly popular and more efficient in the last couple of years, and that’s especially true for at-home direct-to-consumer genetic testing.

In 2018, the U.S. Food and Drug Administration (FDA) approved an at-home DNA test for genetic mutations linked to breast and/or ovarian cancer. This specific test is designed to let you know whether or not you have certain genetic mutations that greatly increase your risk for breast cancer — but who should rely on such a test? And do the results definitively tell you whether or not you’ll develop breast cancer in the future?

“While the self-test is easy to complete, and you can do it conveniently from your home, its usefulness is limited,” cautions breast cancer specialist Shimoli Barot, MD.

Dr. Barot explains how the FDA-approved at-home DNA test for breast cancer works, who should seek it out and other alternatives you may want to consider.

How to test for the breast cancer gene at home

Genetic testing for hereditary breast and ovarian cancer looks specifically for mutations on the BRCA1 and BRCA2 genes. BRCA gene mutations produce a much higher risk for breast and/or ovarian cancer than what is seen in the general population. These mutations are inherited, meaning they’re passed down from your biological parents and can run in your family.

The at-home DNA test doesn’t need a prescription, can be ordered online and requires submitting a saliva sample. A lab analyzes DNA from cells in your saliva to look for three pathogenic variants in the BRCA genes (two in BRCA1 and one in BRCA2).

How accurate is the test?

There are at least 1,000 known BRCA mutations. But the FDA-approved BRCA genetic test for breast cancer specifically looks for three “founder mutations” that are most common in people of Ashkenazi or Eastern European Jewish ancestry. These three mutations aren’t typically seen outside of these populations.

When you’re of Ashkenazi descent, your chance of having a BRCA1 or BRCA2 gene mutation is an alarming 1 in 40, compared to 1 in 400 to 500 for the general population.

“The DNA self-test is a pretty good screening for most people with Ashkenazi Jewish ancestry, but it may not go far enough,” notes Dr. Barot.

While the at-home test screens for the BRCA1 and BRCA2 mutations that account for 80% to 90% of the cancer-causing mutations seen in the Jewish community, it doesn’t evaluate other high-risk genes, including other BRCA genes and non-BRCA gene mutations associated with high risk for breast cancer. It also doesn’t take into consideration non-genetic factors that can increase your risk for breast cancer.

“Additionally, families may share other less significant genes or environmental exposures that contribute to risk, even when a specific gene mutation is not identified,” states Dr. Barot. “So, patients whose home DNA tests are negative may still benefit from MRI screening or preventive medication.”

If you are of Ashkenazi Jewish descent and have a family history of breast cancer, the at-home test is still an excellent resource. But if these factors don’t apply to you, the at-home test may not be as significant as getting more thorough genetic testing from a healthcare provider.

What does it mean if you test positive for a BRCA mutation?

If you tested positive for a BRCA mutation, share your results with a healthcare provider who can determine an action plan for reducing your risk for breast cancer. A positive test does not mean you will develop cancer, but it certainly increases your chances. In many cases, your healthcare provider may suggest enrolling in further genetic testing or genetic counseling to confirm your test results and any other genetic mutations you might have.

What does it mean if you test negative for a BRCA mutation?

If your at-home test is negative, it doesn’t rule out the possibility of carrying other genetic mutations that increase your risk for cancer. It also doesn’t rule out the possibility of developing cancer down the line. If your test is negative and you have a family history of breast cancer, you should talk to your healthcare provider about other cancer screenings you can do to assess your level of risk.

Should you see a genetic counselor?

Dr. Barot recommends working with a genetic counselor regardless of ancestry if you have:

• A strong personal or family history of breast cancer.
• Any personal or family history of ovarian cancer, male breast cancer or pancreatic cancer.

The genetic counselor can help you understand which test is best, anticipate possible results, discuss risk reduction strategies and interpret test results.

Having a gene mutation doesn’t mean you’ll get cancer; it only means your risk of cancer is higher. Options for managing your risk include being watched more carefully, considering medication to reduce your risk or even pursuing risk-reducing surgeries.

“Finding out you are at high risk for breast or ovarian cancer is worrying but it also allows you a best path forward,” reassures Dr. Barot. “Having a relationship with a healthcare provider beforehand that you can turn to afterward — especially if the news is rough — is important. I think that’s really missed with at-home testing.”