Home DNA Testing for Breast Cancer: What You Need To Know

Healthcare professionals are glad growing numbers of people want to learn more about their genetic makeup and how it might affect their health.  What worries them is if people are learning enough.

Ryan Bisson, a cancer genetic counselor with Orlando Health, had a mixture of thoughts after learning the US Food and Drug Administration had approved the first direct-to-consumer test that detects some DNA mutations associated with breast cancer.

“It was big news in the genetic counselling community,” he said.  “The immediate impact is that consumers can skip over the geneticist and go straight to the lab.”  Understanding what those lab results mean, however, “becomes a trickier situation.”

That sentiment was echoed by Erica Ramos, president of the National Society of Genetic Counselors, who issued a statement in reaction to the FDA announcement, warning that “although this test may help to identify people who have a previously undetected BRCA mutation, there are several limitations and the results may be confusing or misleading without appropriate education.”

The test is provided by 23andMe, a personal genomics and biotechnology company that has been marketing direct-to-consumer tests for years. Its saliva test provides customers with all sorts of information about their genetics, some seemingly trivial, and some serious.  The company is now allowed to tell its customers if they have any of three BRCA gene mutations that are found most commonly in people of Ashkenazi Jewish descent, and that are associated with an elevated risk of breast and ovarian cancer.

“This information may be helpful if you follow up with a health care provider,” said Bisson.  But it also opens the door for all sorts of misunderstandings.  In addition, the indications for genetic testing and the scope of genes to be tested are evolving. It takes a specialist like a geneticist or genetic counselor to keep up with the latest science. 

Breast cancer is a scary topic.  It is the second-most deadly cancer afflicting American women.  The American Cancer Society says 260,000 women and a few men will be diagnosed with the disease this year, and nearly 41,000 will die.  But of those cases, said Bisson, genetics will have played a role in only about five percent.  And the potential for misplaced attention, emphasizing genetics over other factors is concerning to genetic counselors.

Normally, BRCA genes function as safeguards against cancer, explained Bisson.  They are “tumor suppressor genes.” They protect cells from growing out of control and developing into the disease. Healthy BRCA genes repair genetic errors that can occur when cells multiply, for example, which is why an improperly functioning or mutated BRCA gene – though rare among the general population – can sharply increase cancer risk. 

Testing positive or negative for certain mutations is merely one of several factors. Family history, ancestry, lifestyle, and environment all play roles. A genetic counselor works with patients to review all of these factors.  
Critics of the direct-to-consumer tests say going through all of these details is a lot of work. Genetic counselors interview patients, discuss their family histories, calculate the risks and then, if they are suspicious of a genetic factor, discuss testing.  Sometimes, Bisson said, it may be more helpful to begin with genetic testing of other family members, a mother or aunt, for instance, before testing the patient.  The role of the genetic counselor, said Bisson, is to help the patient make informed decisions. 

Without this context, the usefulness of many direct-to-consumer genetic tests has been regarded skeptically by leading health organizations like the Centers for Disease Control.  That agency said bluntly, “… We include personal genomic tests as ‘tier 3’ tests. Such a rating implies that there is no evidence for clinical validity or utility of such applications in healthy individuals in the population.”

Worse than questionable utility, according to Bisson, is the concern consumers may regard a negative score on their genetic test as a clean bill of health, or they may regard a positive one as a need for aggressive intervention.  Without proper counseling, either reaction could have serious repercussions.  We have had patients state that “I will get genetic testing and if the results are normal, I will not have to undergo mammographic or other breast cancer screening” stated Dr. Rebecca Moroose, medical director of the Cancer Genetics and High Risk Center at Orlando Health UF Health Cancer Center.  This is a very uninformed response as 90 – 95% of breast cancers are not related to an inherited mutation. 

As the availability of direct-to-consumer genetic tests grows, primary care physicians and other frontline health care providers will need to be aware of how this may affect their interactions with patients.  According to the CDC, a 2016 survey of people who underwent personal genomic tests found that most of those tested who shared results with their health care providers were not satisfied by the reaction of their providers. In fact, many providers, according to the survey, questioned medical actionability of the test results and showed lack of engagement or interest.  These may represent missed opportunities to help educate and inform patients.  

“There is no national protocol” for how doctors should address findings in these tests, observed Bisson.  This will be a growing issue.  “We want people to be fully informed,” he said. “But this can be so complex, especially cancer genetics, that we recommend some sort of genetics professional involved.”

Ryan Bisson, MS, CGC, is a genetic counselor at Orlando Health UF Health Cancer Center, and Rebecca Moroose, MD, is medical director of the Cancer Genetics and High Risk Center at Orlando Health UF Health Cancer Center.

For more information, visit OrlandoHealthCancer.com.