The story focuses on a recent decision by the FDA to approve a genetic test by the company 23andMe which screens for several gene mutations associated with an increased risk of breast cancer.
The story is a brief one, yet does mention some of the caveats associated with the testing. However, the story essentially relies on news releases from the FDA and 23andMe to inform readers, offering little insight into the cost of the testing, the accuracy of the testing, or the extent to which testing positive for the relevant gene mutations may affect one’s risk of developing breast cancer. Other stories, like this skeptical take in the Philadelphia Inquirer and this piece from The Atlantic, are somewhat longer and offer additional information that provides valuable context.
The CDC notes that–with the exception of some types of skin cancer–breast cancer is the most common form of cancer in U.S. women. In other words, breast cancer is something that many women worry about. Meanwhile, tests for mutations in the BRCA genes that can pose an increased risk of breast cancer have garnered widespread media coverage in recent years, thanks (at least in part) to Angelina Jolie’s highly-publicized decision to have a double mastectomy after testing positive for relevant mutations.
Genetic testing is much more complicated and nuanced than getting a cholesterol level. Proper education and counseling by a physician with experience in cancer genetics and/or a genetic counselor is essential when deciding whether or not to be tested. It’s also important when deciding what test to perform, and for assistance in understanding the significance and implications of positive, negative or indeterminate test results.
In this instance, the story doesn’t convey that complexity or offer much information that readers can use to make decisions about the use of the recently-approved 23andMe test. For example, what is the rate of false positive results? Or false negatives? What does that mean for actual risk of developing breast cancer? And how much does it cost?
Cost isn’t mentioned. The BRCA testing appears to be part of the $199 “health + ancestry service” package provided by 23andMe — though the package description on the company website did not include BRCA at the time of this writing. While this is a significant out-of-pocket expense for most people, it is somewhat less expensive than some other genetic testing options. However, those other testing options are significantly more extensive. In other words, as one genetic counselor notes in a related article in The Atlantic, “[23andMe] is not an inexpensive way to get your testing done more cheaply.”
The benefits in this context would, presumably, be an increased awareness of one’s risk for breast cancer; information that can be used to make informed decisions about monitoring and prevention. However, the story does not use numbers in a way that would help women choose the best course of action. For example, it does not explain how accurate the test is, nor does it tell readers how much their cancer risk is increased with a positive result. It also does not explain what women might do to mitigate that increased risk, and how much their risk would decrease as a result.
While it might be too much to ask the story to include all of this information, providing at least some of these numbers would be necessary to meet our expectations for this criterion.
There are questions about accuracy that will be discussed under quality of evidence, but we think it’s worth addressing potential harm associated with any screening test: false results. The Mayo Clinic notes that testing positive for a BRCA mutation can cause “Feelings of anxiety, anger, sadness or depression”; “Difficult decisions about preventive measures that have long-term consequences”; and “Feelings of inevitability that you’ll get cancer.” Those are serious stresses associated with accurate diagnoses. Those same stresses can occur if someone is inaccurately told that they have a relevant gene mutation — and that’s a potential harm that is worth mentioning.
Another potential harm is if a patient is found to have a “VUS” – variant of uncertain significance. This is an abnormality in the gene which may or may not be harmful. When patients undergo genetic testing under the care of their physician or genetic counselor, the possibility and implications of a VUS are explained prior to and after testing. As the 23andMe testing kit is available to the consumer without a prescription and without a requirement for pre-test education or counseling, patients may be further confused if the results reveal a VUS.
There is no discussion of the medical evidence behind this test. How well-tested it is? How much science supports it use? What kind of evidence is required for FDA approval?
Let’s also talk about accuracy itself. In any medical test there are two types of accuracy: sensitivity and specificity. Sensitivity refers to how accurate the test is at detecting a problem in people who have that problem. Specificity refers to how accurate the test is at determining there is no problem. And these things tend to be a bit of a trade-off. i.e., tests with a high sensitivity have a low false-negative rate, but are likely to have a higher rate of false positives; whereas tests with a high specificity have a low false-positive rate, but are likely to have a higher rate of false negatives.
What are the sensitivity and specificity for the 23andMe tests discussed in this story? The story doesn’t tell us. That said, the story does get credit for noting that the 23andMe test only tests for “three out of more than 1,000 known BRCA mutations” — and that those three mutations are found predominantly in people of Eastern European Jewish descent. That’s valuable context for highlighting the limitations of the testing.
The story provides useful information from an FDA news release and clearly notes that the relevant testing is a test being marketed by a specific company. That said, the story lacks actual interviews with third-party expert sources not connected with the FDA or the gene testing company.
The story may actually confuse readers on this count. The story says: “The prescription-free test is the first to report on three specific BRCA1 and BRCA2 breast cancer gene mutations, according to the FDA.” That’s awkwardly phrased. It would be more accurate to say that this is the first test you can get without a prescription that reports on these three mutations. 23andMe is not the only company that provides genetic testing for BRCA mutations, and the story does not make sufficiently clear to readers that there are other genetic tests available that evaluate a broader range of potential mutations. It’s just that these other tests aren’t made available directly to consumers.
The story doesn’t make it clear when this test will be available. The company’s website notes that said testing results will be available “in the coming weeks.”
The story does address the novelty here, but does so in an awkwardly phrased way. However, we addressed that under “Compare alternatives.” We don’t want to ding the story twice for the same thing, so we’ll let it pass here.
23andMe issued a release — and so did the FDA. As far as we can tell, all of the material in the story was drawn from these two releases.
Systematic, Criteria-Driven
Monday at #ADA2021, an infectious disease epidemiologist, a journalist, and a researcher shared perspectives on communication of risk in the era of COVID-19: http://ow.ly/ROfR30rMeE7 @AstleyCM @garyschwitzer @berthahidalgo @ADA_DiabetesPro
Shoutouts to @susan_bewley @drkevinknopf @MichaelBaum11 in this call for more than fawning coverage from press releases for these kinds of stories.
Also, linked history inside goes back 5 years just on Grail apparently trying to become Holy Grail. https://twitter.com/garyschwitzer/status/1408849696416841731
Comments (1)
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Russ Poter
March 9, 2018 at 7:51 amIMHO, the greater issue is how much data-security is involved. Please — common sense. What would happen if one’s employer and/or insurer somehow found out that one had the cancer gene, or T1 diabetes, or something else? Not good, IMHO. And that, IMHO, that is the real 800-pound beast in the room.
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