Diseases & Conditions

New Direct-to-Consumer Breast Cancer Genetic Tests: A Good Idea?

By on 03/22/2018

The direct-to-consumer genetic testing service 23andMe has the go-ahead from the U.S. Food and Drug Administration to tell its customers whether they test positive for three mutations in two genes commonly associated with breast cancer.

Is that information helpful?

On the contrary, says Einstein Healthcare Network geneticist Adele Schneider, MD: “It’s a dangerous thing to be doing for the general population.”

For a fee, consumers can provide a sample of their saliva in a tube to 23andMe for analysis. After six to eight weeks, customers receive what the company describes as “75+ reports on health, traits and ancestry.”

With the FDA’s recent approval, 23andMe is authorized to report on two mutations in the BRCA1 gene and one in the BRCA2 gene. Inherited mutations in these three genes are most commonly associated with an increased risk of breast cancer. (There’s also an association with ovarian cancer, prostate cancer and others.)

On the surface, that might seem like a good idea. The problem, Schneider says, is that “there are at least a thousand mutations” in the BRCA1 and BRCA2 genes – and 23andMe is only testing for three. Plus, the mutations in question are most commonly associated only with people of Ashkenazi Jewish heritage, a population where there’s a markedly higher risk of being a carrier of one of these mutations.

As a result, most 23andMe subscribers are not likely to test positive for the three mutations being tested for, but they may still be at risk for one of the thousand or so possible additional mutations. That, she says, is a serious concern because it creates a false sense of comfort.

“They might then think, ‘I’m negative, so I don’t have an increased risk of breast cancer,’” Dr. Schneider says. “In the end, ironically, there could be an increased incidence of breast cancer because people were given a false sense of security and stopped having routine mammograms.”

23andMe suggests that testing for those three gene mutations is useful because those mutations have a comparatively high prevalence among people of Ashkenazi Jewish heritage, and many don’t know they share that heritage.

In an announcement following the FDA authorization, 23andMe notes that “current clinical guidelines for genetic risk evaluation are based primarily on personal and/or family history of certain cancers.” Often, the company says, those guidelines overlook those who do not self report Ashkenazi Jewish heritage. “Consistent with … previous findings, 23andMe found that of those BRCA carriers who gave family medical history, about half reported no history of cancer in first-degree relatives,” the company states. “23andMe has also observed that many of its customers for whom Ashkenazi Jewish ancestry was detected, did not self report any Jewish ancestry. These individuals might fall outside the guidelines of clinical testing.”

The company also acknowledges that the test “doesn’t account for all genetics variants that can cause a higher risk of cancer, and people should continue with their recommended cancer screenings.”

Dr. Schneider strongly disagrees with that rationale. Screening in the absence of input from an informed medical professional, she says, leaves far too much unexplained and poorly interpreted, if at all. She is concerned that those who test negative for these three breast cancer gene mutations may not read or disregard the company’s advice to continue recommended screenings. For that kind of advice, there is no substitute for medical intervention.

“If you are doing something medical,” she says, “then you need a medical professional to support you. They’re not providing medical care nor medical answers on the 23andMe website.”

In the absence of expert medical advice, Dr. Schneider adds, even people who receive a positive result may not understand the urgency. “They may not understand that it is an action item,” she says.

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