What You Can Learn About Your Breast Cancer Risk From 23andMe
The FDA has approved a genetic test from 23andMe that can tell you if you have any of three specific mutations in the BRCA1 and BRCA2 genes that increase your risk of breast cancer. But these are only three of the more than 1000 such mutations in the BRCA genes, and they are not even the most common.
However, they are present inabout 2 percent of people of Ashkenazi (Eastern European) Jewish descent, and a 23andMe spokesman says they account for over 90 percent of the deleterious BRCA mutations in this population. Women with one of these options are 45 percent to 85 percent more likely to develop breast cancer by age 70. Men with these options also have an increased risk of breast and prostate cancer. 23andMe CEO Ann Wojcicki said in a statement that the test is “incredibly valuable for those who may not know their Ashkenazi Jewish origins or have a family history of cancer.”
(23andMe offered this test before the FDA took drastic measures to withdraw its medical tests from the market until they were individually approved. Today’s announcement marks the first FDA approval for a test for genetic risk of breast cancer that is not required doctor’s appointment.)
But your results do not represent what you might have expected. A negative test result for these three variants does not mean that you are clean, regardless of your origin: you may still have other mutations that increase your risk of cancer. The converse is also true: you can get a positive result on this test without having to rush to hormones or surgery.
The FDA’s test statement warns: “Consumers and healthcare professionals should not use test results to determine any treatments, including anti-hormone therapy and prophylactic breast or ovarian removal. Such decisions require confirmatory testing and genetic counseling. ” In short: if you test positive, call your doctor to find out what to do next.