At-Home DNA Tests for Breast Cancer Risk Have Limitations

Over the last decade, it’s become easier than ever to conduct certain health tests and screenings from home — and the tests themselves have become more effective, too. That’s especially true of 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 changes, or mutations, linked to breast cancer and/or ovarian cancer.

“The self-test is easy to complete, and you can do it conveniently from your home,” says cancer genetic counselor Ryan Noss, MS, CGC. “But there are some significant limitations to its usefulness.”

Noss explains how at-home DNA testing for breast and ovarian cancer works, who may benefit and when to see a genetic counselor instead.

How to test for the breast cancer gene at home

At-home testing for breast and ovarian cancer is designed to reveal whether you have certain genetic changes that raise your risk of developing these types of cancer.

Everyone has BRCA1 and BRCA2 genes. You’ll often hear them referred to as BRCA, but healthcare providers use the term “BRCA1/2.”

“Genetic mutations are changes to your DNA sequence,” Noss explains. “Specifically, at-home testing for breast and ovarian cancer looks for mutations on the BRCA1 and BRCA2 genes. These inherited mutations can run in biological families.”

People with BRCA gene changes have a significantly higher risk of developing breast cancer and/or ovarian cancer than the general population.

At-home DNA tests analyze DNA from cells in your saliva to look for three cancer-linked variants in the BRCA1/2 genes (specifically, two in BRCA1 and one in BRCA2). The test:

• Doesn’t require a prescription
• Can be ordered online
• Requires you to submit a saliva sample by mail

How accurate are at-home tests?

The FDA-approved BRCA1/2 genetic test for breast cancer specifically looks for three “founder mutations” that are most common in people of Ashkenazi (Eastern European) Jewish ancestry.

Importantly, these three mutations aren’t often seen among other demographics. In fact, an estimated 1 in 40 people of Ashkenazi descent carry one of these founder mutations, compared with just 1 in 400 to 500 for the general population.

So, does at-home genetic testing work?

“The DNA self-test is a pretty good screening for many people with Ashkenazi Jewish ancestry,” Noss says. “But it may not go far enough.”

Here’s what at-home tests don’t evaluate:

• Other BRCA gene mutations: The three founder mutations account for 80% to 90% of cancer-causing mutations in people of Ashkenazi descent. But there are at least 1,000 known BRCA mutations, and these tests don’t screen for others.
• Non-BRCA gene mutations: BRCA gene mutations aren’t the only ones associated with a high risk for breast cancer. Others, like PALB2, TP53, CHEK2 and ATM, increase cancer risk, too.
• Non-genetic factors: “At-home testing doesn’t evaluate non-genetic factors that can raise your risk for breast cancer,” Noss notes. Family history can still be important, even if the test doesn’t find a cancer-related gene mutation.

Understanding your test results

So, you’ve done an at-home test. When your results come back, what then?

If your test is positive for a BRCA mutation

A positive test doesn’t mean you will develop cancer, but it does increase your chances.

“It’s important to share your results with a healthcare provider who can determine an action plan for reducing your breast cancer risk,” Noss advises.

Your provider may recommend doing further genetic testing or genetic counseling to confirm your test results and identify any other genetic mutations you might have.

If your test is negative for a BRCA1/2 mutation

If your at-home test is negative for a BRCA1/2 mutation, it doesn’t rule out the possibility of carrying other genetic mutations that increase your risk of 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 still talk to a healthcare provider about other cancer screenings you can do to assess your level of risk,” Noss further advises.

When to see a genetic counselor

If you’re of Ashkenazi Jewish descent, at-home testing may be a reasonable starting resource. But many people are better served by more thorough genetic testing, especially those with a strong personal or biological family history of:

• Breast cancer, including male breast cancer
• Ovarian cancer
• Pancreatic cancer

“A genetic counselor can help you understand which test is best, anticipate possible results, discuss risk reduction strategies and interpret test results,” Noss says.

It’s important to remember that 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 may include:

• More careful monitoring
• Medication that reduces your risk
• Risk-reducing surgery, like preventive mastectomy

Learning that you’re at high risk for breast or ovarian cancer can be worrying. But it also allows you to figure out the best path forward.

What’s right for you will depend on ... well, you — your test results, your personal and family history and your overall health. And your healthcare providers will be there every step of the way.

“In-person genetic counseling and testing gives you the chance to build a relationship with providers who you can turn to for guidance and support,” Noss reassures. “That’s something that at-home testing can’t provide.”