Should We All Be Tested for Cancer Predisposition Mutations?

To test or not to test, that is the question.

Posted May 30, 2017

There is a big problem in the world of cancer genetics: Most people who have a mutation in a gene that predisposes them to developing cancer don’t know they have it. They also don’t realize that knowing whether they carry a mutation could help them make choices that could save their lives and the lives of their family members.

For example, one of the top CDC recommendations for preventing colon cancer is to diagnose and manage Lynch syndrome, the most common hereditary cause of colon cancer, which affects approximately one in 300 individuals. Despite this, only a few percent of the individuals who have Lynch Syndrome have been diagnosed with it in the United States.

So why do so few people get tested?

One reason is ignorance. Because many patients are unaware of the potential benefits of genetic testing, they are not motivated to get the test done in the first place. In general, most people opt to get tested when they know they are at risk due to their family history, especially since insurance will only pay for a test if you or your family members have been diagnosed with a specific type of cancer. But even this knowledge can be difficult to acquire given that families have become smaller in recent generations—reducing the chances that an inherited gene will manifest as cancer—and that many people simply don’t like to disclose their diagnoses to their loved ones.

Ignorance is also a problem in the medical community. Many doctors don’t even know what test to order. In our clinic we recently saw a patient whose family had a BRCA mutation running through the bloodline, but his doctor ordered the wrong test (BCR/ABL instead of BRCA.) and informed him that he did not carry the mutation. This reminds me of the famous Mark Twain quote: “The difference between the right word and the almost right word is like lightning and lightning bug.”

Unfortunately, another factor that discourages people from getting tested, is the fear that they will be discriminated against for things like jobs or insurance plans if their results are positive. This fear is understandable but also unfortunate, given that the cost of cancer treatment outweighs the cost of preventative care.

An ideal solution would be to make genetic testing part of routine medical care, much like immunizations, for all adults regardless of family or personal cancer history. Because of the rapid rate at which scientists are discovering new cancer genes, such tests would need to be performed every two to five years in consultation with the patient’s primary care physician and a genetic counselor who could help make sense of what the results actually mean. 

Of course, ideal solutions are rarely available. For one thing, the world has a shortage of trained cancer geneticists, so we’d need to start by training more genetic counselors, counseling assistants, and other genetic specialists. This, as well as improvements to how counselors can more efficiently communicate with patients, is an ongoing effort in the genetics community.

In a recent article in the Journal of the American Medical Association, Dr. Mary Claire King stated that “to identify a woman as a [BRCA mutation] carrier only after she develops cancer is a failure of cancer prevention.” But rather than call for routine testing for all adults, Dr. King and her colleagues only went so far as to propose giving women BRCA1/2 tests at around age 30. This is certainly a start, but given that there are several other common cancer genetic syndromes (e.g. Lynch Syndrome, as mentioned above), it would hardly solve the entire problem.

Beyond the obvious benefit of arming individuals with powerful information that will allow them to take action that could potentially save their lives, genetic testing also offers a host of other benefits. Namely, it will provide a trove of data from our entire population of patients that will allow scientists to augment their own research into the genome.

Of course, even global screening would bring its own set of complications. For one thing, the fear of discrimination mentioned earlier is not unfounded, so we would have to put protections in place for patients who are most at risk. Meanwhile, the shortage of experts available to explain the test results could leave patients feeling ill-informed about the harms and limits of their newfound knowledge. And given that we are discovering new and more information every day, patients and doctors would have to be prepared to adapt their approach to testing and care. Having one negative test result does not ensure you are out of the woods for good.

And, while knowing the truth about your cancer risk allows you to make decisions that could protect you down the line, it doesn’t make those decisions any easier. For example, knowing you are at risk for breast cancer does not make it easier to have a double mastectomy at age 35. And, while watching a loved one battle cancer is terrible for families, making the decision to have a hysterectomy or elect for another major surgical procedure can also carry a heavy burden.

Finally, just because we are given knowledge, does not mean we will choose to act on it. Humans are still humans, after all, prone to behaviors that don’t always serve our best interests. Smoking cessation, regular exercise, limited alcohol consumption, vaccinations—these are among the most important steps we can take to increase our chances of a long, healthy life, but if a bad habit isn’t disrupting the fabric of our current, daily life, we’re less motivated to quit it.

For example, we just counseled a 40-year-old nurse with a BRCA1 mutation who had known about her mutation for three years, but didn’t want to deal with it. Finally she saw a new gynecologist who told her the mutation was a “death sentence” only then did she decide to have the recommended surgeries and alert the rest of her family. This, let me remind you, was a nurse.

Knowing what’s good for our future health is just the beginning. We all have those pesky thoughts that we should get the colonoscopy this year or that vaccine last month. Then we hurry on with our day-to-day lives, telling ourselves it’s not that urgent. But what might happen if we could make prevention easier? Not a nuisance or a nice-to-have, but an empowering act that can help you and your family members lead long, healthy lives? Perhaps that is the real question.