U.S. regulators have approved the first genetic test a woman can take at home to check her risk of developing breast cancer — but its focus is narrow, essentially applying only to Ashkenazi Jews.
No doctor’s prescription will be needed for the test, which was developed by 23andMe.
The test assesses the three most common BRCA gene mutations found in people of Eastern European Jewish descent. The U.S. Food and Drug Administration noted that while the mutations are present in roughly 2% of these women, they rarely occur in other ethnic populations. Prevalences in non-Jews range from 0% to 0.1%.
Also, there are more than 1,000 BRCA mutations. So a negative test result, either in women of Ashkenazi Jewish descent or in other ethnic populations, does not rule out the possibility that a woman has other BRCA mutations that increase her risk of cancer.
The test analyzes DNA from a saliva sample. Because BRCA mutations increase the risk of breast, ovarian, and prostate cancer, the test’s readout lists a woman’s risk of breast and ovarian cancer, and a man’s risk of breast and prostate cancer. Men can develop breast cancer, too, although it is far less common.
“This test provides information to certain individuals who may be at increased breast, ovarian or prostate cancer risk and who might not otherwise get genetic screening,” FDA official Donald St. Pierre said in a press release. It is “a step forward in the availability of [direct-to-consumer] genetic tests,” said Pierre, the acting director of the Office of In Vitro Diagnostics and Radiological Health at the FDA’s Center for Devices and Radiological Health.
“But it has a lot of caveats,” Pierre added. “While the detection of a BRCA mutation on this test does indicate an increased risk, only a small percentage of Americans carry one of these three mutations, and most BRCA mutations that increase an individual’s risk are not detected by this test.
“The test should not be used as a substitute for seeing your doctor for cancer screenings or counseling on genetic and lifestyle factors that can increase or decrease cancer risk,” he advised.
The FDA also cautioned that no doctor or patient should use the test as a basis for deciding treatment, “including anti-hormone therapies and prophylactic [preventive] removal of the breasts or ovaries.” Before making such decisions, patients who have taken the test at home should have medical professionals test for BRCA mutations as well.
The FDA’s approval decision was based on the test’s accuracy and reproducibility. Despite this, the agency is setting up special controls to further ensure the test’s accuracy, reproducibility and proper labeling. This will provide additional assurance that the test is safe and effective.