For $100 or so and a little of your saliva, a lab will check your DNA for genetic mutations that put people at a substantially higher risk for certain cancers, mainly breast and ovarian. Internet ads highlight the test’s convenience: No need to visit a doctor’s office; the kit is sent right to your home.
Should you go for it?
The answer for most people is “probably not,” says Deepika Nathan, a UCI Health genetic counselor.
Limitations of home genetic tests
While these home-based tests have been gaining in popularity, they have significant limitations. Genetic testing is most useful when ordered and interpreted as part of a complete evaluation of the person’s medical and family history, Nathan says.
In March, the U.S. Food and Drug Administration approved direct-to-consumer kits for three specific mutations in the BRCA1 and BRCA2 genes. These “tumor suppressor genes” normally protect people against several kinds of cancer. Mutations within these genes can interfere with that protection. The difference can be striking.
“Mutations in these genes can greatly increase the risk for breast, ovarian and other cancers,” Nathan says. Lifetime risks for developing breast and ovarian cancer for most women are about 10% and 3%, respectively. For a woman with a BRCA mutation, however, the lifetime risk for breast cancer can be up to 80%. Her lifetime risk for ovarian cancer is also increased.
The three specific mutations included in the BRCA1 and BRCA2 home test can be found in people of any ethnic background, but they occur more commonly in the Ashkenazi Jewish population — Jewish people of Eastern and Northern European heritage. Even in that group, the risk of having one of the mutations is still small at about 2% — but that may be high enough for some people to want the test.
False reassurance is a risk
However, several hundred other BRCA mutations are associated with an increased risk of cancer, and these can turn up in people of any ethnic background. Many of those mutations may be missed if the laboratory checks only for the three in the FDA-approved test.
A negative finding may give people a false sense of reassurance and lead some to think they do not need closer medical attention, when their personal or family history may indicate cause for concern.
Before ordering a home test, Nathan says people should look for certain risk factors, such as a family history of one of the cancers involved or the patient’s own history of cancer. Breast cancer in a woman younger than 45 (or in a male at any age) is a sign that testing might be a good idea.
What to do if you test positive for BRCA
People who test positive for BRCA mutations may want to consult their physician about increasing screening, such as more frequent mammograms and breast MRIs to detect breast cancer early, when it is more treatable. Or they may consider risk-reducing strategies, such as surgery to remove breast tissue.
Screening for ovarian cancer is not as effective and women with these mutations often consider preventive removal of their ovaries and fallopian tubes in their 40s.
Genetic testing may be relevant whether the client is male or female, Nathan says. A man’s risk of male breast cancer increases if he has one of the mutations, as does his chance of developing certain other malignancies, such as prostate and pancreatic cancer. His relatives also may be at risk.
Genetic testing may also be helpful for people who don’t know their family medical history, including people who are adopted.
A genetic counseling meeting is crucial
No matter what, Nathan highly recommends genetic counseling before taking any tests. A counselor is trained to sift through all of the factors involved and determine whether it makes sense to do any testing, and if so, what kind.
“It is absolutely important for people to consider having appropriate genetic testing based on personal and family history after a detailed discussion,” she says.
People might not think they live near such an expert, but chances are they do. Nathan urges people who think there might be reason for concern to visit the website of the National Society of Genetic Counselors, where they can click on a searchable database of qualified counselors by location.
Accuracy not always assured
Accuracy is another concern, Nathan says. The FDA-approved home kits are very accurate — when they are testing for the three BRCA mutations. But many testing companies are doing a full panel of tests, not just those three. And those additional tests may not be FDA-approved or as reliable.
Further, people might think they are safe when the results are negative, when in fact they were not tested for the most relevant genes based on their own family history, she says. Still others may be alarmed about results that turn out to be a false positive once additional clinical testing is done.
When cost is a consideration, the home kit may be cheaper than a test that might be prescribed by your doctor. But most insurance companies cover the cost of testing when health professionals have determined that you meet the criteria, the genetic counselor says.
Nathan doesn’t rule out using the home kits. But first, she advises, become informed. Then make sure you take a test that makes the most sense for you.
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