What genetic tests did not tell me about my cancer

"What do you share with Dad, this Father's Day, celebrate your DNA connection with Dad."

This was the slogan of the 23andMe personal genomics company's marketing campaign for Father's Day. Now, a week later, fathers send their DNA results. What will their gift actually reveal about the genetic traits that they have passed on to their children? In my case, it's a gene that exposes my father and me to a high risk of cancer.

The United States Food and Drug Administration (FDA) has approved the first genetic health risk test directly from consumers last year. As a doctor, I see this as a truly incredible scientific breakthrough. Yet, of course, there are reservations.

No matter who can order 23andMe – with less than $ 150 and a small tube of saliva, you can learn a lot about your ancestry, from where your family comes from and with whom you could be related. Even more than learning about your ancestry, you may be interested in the medical implications of the results – for example how much your body can handle certain medications, or caffeine. Or if you are at risk of allergies, heart disease … or even cancer.

Knowing this information does not seem anything other than a positive on the surface. If you knew early in your life that you were predisposed to heart disease, it might encourage you to exercise more often and limit excessive indulgence in high-fat foods. Optimistic, there could be great benefits to this knowledge.

However, are you really ready to learn that your 5-year-old daughter carries the BRCA gene? The gene that could give him a 70% chance of having breast cancer and other cancers like ovarian and pancreatic cancer?

Given the enormity of what our genetic code implies, we may want to weigh the consequences of knowing more about our DNA. And if as consumers we can really manage what we could learn from the fate of ourselves and our children. How can we console the anxieties of a devastated father who logs on to the website for his late-night findings and discovers that he has passed on one of the most feared cancer genes to his children? This father could have been my father.

Without the support of a health care provider giving context and advice, how much knowledge is too much? It is important for consumers to be able to communicate with a health care professional to fully understand the data they receive and their context.

The 23andMe test is not intentionally misleading. But on the other hand, it is important to understand that knowledge itself also has limitations. You will only discover the risks of the BRCA gene if both of your parents are of Jewish origin. That explains why when I read my 23andMe results, there was nothing about BRCA – my Swiss-French ancestry made it improbable, just like the fact that I had not had any money. other high risk factors. Still, I have the BRCA mutation and I have had breast cancer.

As a physician, I clearly understand the scope of the BRCA tests offered by this specific test. By reading carefully all the disclaimers, I would have known that with my ancestry, any BRCA transfer that I could host would not have been tested.

However, even as a physician, I did not fully understand that when my 23andMe test came back as a slightly higher risk of breast cancer, it would make no sense to me.

So, how can we expect the general consumer to understand this?

We live in an environment increasingly focused on information and data and have access to enormous opportunities for early medical interventions. Knowledge is usually a very good, highly empowering tool with appropriate medical context and support. But as consumers, when you order a test that claims to tell you about your cancer risk, it's important to understand the limitations of the information you receive.

The FDA's approval of the 23andMe test is an important milestone. The test offers a fascinating insight and, hopefully, useful and enlightening on his ancestry. The harmful BRCA mutations deserve to be known, especially because the mortality that they can cause can be reduced significantly by preventive measures. When we are dealing with consumer-oriented testing that can help solve and / or raise important health issues, we, as consumers, need to understand the fine print.

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Dr. Pamela Munster is a breast cancer specialist and lead researcher on BRCA mutations. She is the author of the upcoming book "Twisting Fate: My Journey with BRCA – From Breast Cancer to Patient and Back" (September 2018).