Genomic sequencing in primary care: Promises unfulfilled

January 31st, 2019

The Chicago Tribune recently reported that the NorthShore University Health System will be conducting a pilot project of genome sequencing in primary care, making it the latest health system (along with Geisinger and Sanford Health) to offer broad genetic testing as a part of routine primary care. The Tribune touts NorthShore’s initiative as potentially “the future of primary care — a way to keep patients healthier and hold down costs by catching treatable diseases earlier.” Another high-ranking official from a neighboring medical center was quoted in the same article, saying “There’s a lot to be gained for [genome sequencing], and I think there’s very little to be lost.”

Will routine genomic sequencing be the innovation that revolutionizes medicine? Or is it more hype than substance? A timely perspective piece in the Journal of Clinical Investigation from Dr. Michael Joyner at the Mayo Clinic and Dr. Nigel Paneth at Michigan State University explains why genomic sequencing is unlikely to be the “future of medicine” that NorthShore and other health systems promise.

The idea of fully understanding our bodies and preventing future disease by looking at every gene in our DNA is tempting. But Joyner and Paneth pose an important question — does genomic sequencing predict more about our health than family history or social and physical characteristics? They write that despite the promise of the accurate predictive power of DNA, 

“Extensive analyses of thousands of potential gene-health outcomes often fail to match, let alone exceed, the predictive power of a few simply acquired and readily measured characteristics such as family history, neighborhood, socioeconomic circumstances, or even measurements made with nothing more than a tape measure and a bathroom scale.”

This is because few health conditions are connected to just one gene variant, making them difficult to assess disease risk using genetic information alone. Common health conditions such as high blood pressure, diabetes, cardiovascular disease, and many cancers, are each “linked to many hundreds of gene variants that individually and even collectively explain only a small fraction of the variance in disease frequency,” the authors write.

In one example from NorthShore health system, a 29-year-old patient with a family history of breast cancer finds out through genomic sequencing that she has an elevated risk of breast cancer. Her doctor then schedules her for regular mammograms and MRIs. The patient calls the genetic test “empowering” and “amazing.” However, it’s unclear whether this outcome is better for the patient, since it has not been shown that regular screening mammograms, even for women at high genetic risk of breast cancer, have greater benefit than harm before age 35. It’s possible the doctor would not have recommended starting screening so early, but because of the results of the genetic test, they felt pushed to “do something.” In a randomized controlled trial for genomic sequencing compared to family history alone, researchers found that routine genomic sequencing in primary care “may prompt additional clinical actions of unclear value.”

Another myth that Joyner and Paneth discuss is the idea that genetic testing will change patients’ behavior. However, the idea that knowing one’s risk of future disease will motivate someone to change their lifestyle, isn’t actually born out in studies of people who get tested. As the authors point out, why would a patient decide to quit smoking after learning they have a six-fold increased risk of lung cancer, if they haven’t already been convinced to quit by the 20-100x greater risk of lung cancer from smoking? 

Joyner and Paneth are troubled by the increasing investments in genomic testing, when after twenty years, the Human Genome Project has had no positive effect on population health or life expectancy. Should we be funneling money into routine genomic sequencing and other “futuristic” health technology for primary care patients, when so many Americans don’t have access to primary care at all? As the authors write, we have to make sure that our “obsession” with DNA does not preclude research on the many pressing health problems that we need to solve. Otherwise, we will end up with more unfulfilled promises.