Testing Breast Cancer Risk at Home: Is It Worthwhile?

Patient Expert

Have you considered exploring your breast cancer risk via 23andMe’s direct-to-consumer genetic test for cancer risk, approved in early 2018?

My advice? Caveat emptor: Let the buyer beware.

23andMe test gains FDA approval

23andMe had issues with the FDA in 2013, when the government agency sent a warning letter to the company concerning its Personal Genome Service (PGS), which 23andMe subsequently stopped offering.

Still, the company appears to be a reputable vendor offering a solid product: genetic testing to determine ancestry and, more recently, to indicate potential risk for certain hereditary diseases.

And on March 6, 2018, the FDA announced approval of 23andMe’s PGS genetic health risk report for three specific BRCA genetic mutations that are known to increase breast cancer risk.

But how relevant is the test?

The good news: Certain women may benefit by spending $199 to discover if they may be at increased risk for breast cancer. The caveat (emptor): The vast majority of Americans would derive no benefit at all from the test.

What’s the story here? 23andMe’s saliva test covers three of more than 1,000 potential BRCA genetic mutations that can increase risk for breast and/or ovarian cancer. These three specific mutations typically occur in those of Ashkenazi Jewish descent: about 2 percent of American women, according to the National Cancer Institute.

The three mutations occur rarely in women of other ethnic groups: About 0 to 0.1 percent of non-Ashkenazic women carry them. This translates to just more than 15,000 American women of a total non-Ashkenazic population of more than 153 million.

If you decide to take the test

Now, let’s say you look at the odds and still decide to take the test. Happily, you get a negative result — but that doesn’t mean you’re home free. Because only three of more than 1,000 genetic mutations were tested, any of those remaining 1,000+ mutations might increase your cancer risk — something the 23andMe test can’t tell you.

In addition, given the fact that most breast cancers aren’t hereditary, but instead potentially stem from lifestyle issues (lack of exercise, obesity, alcohol consumption), or appear to be totally random — how much comfort would you take from a negative BRCA mutation test result?

Give 23andMe credit: They’re not trying to pull the wool over anyone’s eyes. Educational materials included with test results will let the consumer know that “…most cases of cancer are not caused by the genetic variants in this report. A person could have a variant not included in this test, or could develop cancer for other reasons. A genetic counselor can help you understand how both genetic and non-genetic factors may influence your risk of developing cancer.”

In addition, the FDA cautions that “Consumers and health care professionals should not use the [23andMe] test results to determine any treatments, including anti-hormone therapies and prophylactic removal of the breasts or ovaries,” and that “The use of the test carries significant risks if individuals use the test results without consulting a physician or genetic counselor.”

So even if you spend the money, take the test, and find yourself in the infinitesimal fraction of customers who gets a positive result — you shouldn’t use that result to make any preventive treatment decisions. And if you do, you’re putting yourself at “significant risk.”

If you don’t opt for the test

Given all of this, you might want to consider the following course of action:

  • Understand the relative importance of genes vs. lifestyle in determining breast cancer risk in the general population.
  • Look at your own potential risk factors.
  • If you have any concerns, speak to your doctor.
  • If your doctor determines those concerns put you at increased risk of breast cancer based on your genetics, they can recommend genetic counseling and testing. Testing by a standard go-to company used by medical institutions, such as Invitae, covers up to 26 genetic mutations. And the test, when recommended by a physician, is usually covered in large part by health insurance.

See more helpful articles:

Genetic Counseling: A Tool for Decoding Inherited Cancer Risk

Is Breast Cancer Hereditary?

The Family Connection: New Guidelines for Breast Cancer Genetic Testing