Surge in competition in genetic risk screening warrants caution

A recent article in The New York Times “New Genetic Tests for Breast Cancer Hold Promise” describes new and cheaper tests for BRCA1 and 2 gene mutations that carry added risk for breast and ovarian cancers. Medical guidelines generally limit testing of the so-called “breast cancer genes” to the small percentage of people who already have cancer or whose family history includes breast or ovarian cancers. The test’s high cost ($1,500 and up) is a factor, but the U.S. Supreme Court overturned Myriad Genetics’s patent control in 2013, opening up the commercial development of new tests. Yet the FDA has warned for years now that some genetic testing kits lack clinical validation and should not be marketed due to the potential health consequences of false positive or false negative results.

400px-DNA_Double_HelixAre the tests ready for prime time, and how will the public know? With the rise of commercial genomics applications and the desire for patient-centered medicine, this is a good opportunity for the public to better understand BRCA mutations, preventive surgeries, and outcomes, along with the soundness of genetics tests.

One driver of lower-cost and more widespread BRCA testing is Mary-Claire King, the researcher whose work led to the discovery of the BRCA1 gene. Well respected scientifically and politically (she used genetic information to reunite adopted Argentine children with their “disappeared” birth families), Dr. King calls for all American women over 30 to be tested, hoping to set fears to rest for the vast majority of people while giving the few affected by the genetic mutations an opportunity to make decisions about preventive measures. For this to happen, healthcare policy would need to change. Half of the women with dangerous mutations do not qualify for testing under current guidelines.

Several new developments also promise to make testing for genetic mutations more accessible and far less expensive. The new tests use saliva instead of blood, easier to collect and process. In a rare collaboration, French researchers are joining forces with American rivals Quest Diagnostics and Labcorp to improve the precision of the tests by reducing many non-relevant mutations. The goal is important, but hampered by the fact that Myriad monopolized the data for so many years.

The expansion of BRCA testing bears the hallmarks of many new technological ‘advances’: long on promises to save lives and improve health, and short on evidence to support efficacy and safety. Different companies reveal a wide spectrum of accuracy, from a low 2 percent of BRCA results showing “variants of unknown significance” (those that are non-relevant or unknown) up to higher than 30 percent. The field suffers from a lack of published, peer-reviewed data showing how accurate each new and current test is.

Neither researchers nor patients nor clinicians know what to do with this level of uncertainty. What will a $250 saliva test tell you? If a person gets a BRCA test that comes back negative, how certain is that result? Should people be retested, and how many times? For a woman, a ‘positive’ result that finds a potentially harmful genetic variant may mean the difference between less or more invasive interventions (like having a lumpectomy versus a mastectomy, or keeping one’s ovaries, fallopian tubes, and breasts instead of having them removed ‘preventively’).

A basic question about the accuracy of BRCA and other genetic tests is how they predict actual benefits. How strong statistically are the correlations that link each gene variant to an increased chance of getting, or dying from, a disease by a particular age? Consumers deserve to know how strong that data is (or will be), how many ‘cases’ form the basis of those risk calculations, and for which tests.

Good intentions are laudable. But public health and equitable healthcare requires solid, evidence-based medicine. As health consumers, we must ask tough questions of every medical intervention and demand their answers.

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