Clinical vs. At-Home Genetic Testing
- The field of genetic testing is booming
- Direct-to-consumer genetic tests are shared out of context and without expert guidance as to next steps
- Genetic tests provided by health care providers mean experts can aid in making recommendations for surveillance, determine prognosis and assist in treatment decision-making
There’s reason for the interest: The field of genetics is booming.
Read MoreAssessing Cancer Risk
Comparing DTC to clinical testing for cancer is actually a bit like apples to oranges.
Direct-to-consumer tests, which are relatively inexpensive ($99 and up), can make predictions about people’s health and ancestry. But they’re limited when it comes to offering tests for cancer risk. Currently, the Food and Drug Administration (FDA) has allowed at least one direct-to-consumer genetic testing company, 23andMe, to offer a test for cancer risk; it looks for three specific variations in BRCA1 and BRCA2.
“With direct-to-consumer testing, it’s only a very small piece of the puzzle,” Megan Frone, board certified genetic counselor in the Clinical Genetics Branch at the National Cancer Institute, tells SurvivorNet. “I think about it like a typo somewhere in a novel,” she says. “They’re only looking at three pages,” she says. “You could have a typo anywhere else in the novel that’s breaking that gene and giving you a higher risk for cancer, and they’re just not looking.”
Clinical-grade testing can analyze the risk of 50 different types of cancer, according to The National Cancer Institute.
Doctor Input
A study last year from the National Center for Biotechnology Information notes some other drawbacks, including how DTC tests frequently do not provide conclusive results.
“Most genetic tests performed by DTC companies are limited to few major genetic variants related to the phenotypes of interest, which leads to poor discriminatory power,” it notes.
This means DTC genetic testing does not guarantee that a consumer with a high genetic risk score will suffer from a certain disease, it only indicates a genetic propensity.
Plus, test results could reveal other, unexpected, health risks.
“You have to ask, ‘Are they going to tell me about specific results I might not want to know about?'” Frone says. “Some at-home tests will tell you your risk for carrying certain Alzheimer gene variants. We don’t have any particular treatment for Alzheimer’s. Some people don’t want to know about that stuff because there’s nothing they can do about it. They don’t necessarily realize that they’re going to get that back on a test report.”
All of which points to that important ingredient: an expert who can interpret and make an action plan.
DTC tests are often “conducted without the involvement of a healthcare provider and without an understanding of clinical validity and utility,” notes the Centers for Disease Control.
A recent study based on an online survey of 1,001 adults representative of the population, found that public awareness of genomics and personalized medicine was not increasing in line with advancements in the industry. Seventy-three percent of the survey respondents had not heard of genetic counseling which is conducted by certified health professionals to advise consumers/patients on how to interpret genetic test results.
More Info about Clinical Genetic Testing and Cancer
The first step for someone interested in learning about their risk for developing cancer, according to Frone, is to speak with a health care provider or genetic counselor to learn about options. Then, a risk assessment can be conducted by a certified genetic counselor.
“In this type of consult, they’ll look at personal medical history and family medical history. And, if you’re female, they’ll look at your hormonal risk factors,” Frone explains. “There are computer models to identify risks and patterns within someone’s personal and family history.”
The next step, she says, is to discuss what needs to be done to “test for the potential hereditary cancer syndrome.”
“People need to go into it understanding that genetic testing is really complicated,” Frone says. “To achieve the full value of it, we’ve got to apply the genetic test results in the context of their family health history and their other risk factors to understand final risk. Direct-to-consumer testing is very different from that. It’s more recreational.”
For those identified during the consult as being higher risk, insurance typically covers clinical testing. For people at a lower risk, they may be advised to skip testing altogether, or, they can pay out-of-pocket (costs can vary from $250 or more depending on whether a single gene or the entire genome is being tested).
For example, the BRCA1 and BRCA2 test 23andMe runs has been given the green light from the FDA, meaning "the agency has determined that the benefits of the product outweigh the known risks for the intended use."
This specific test looks at three variants to determine if a woman is at an increased risk for developing breast and ovarian cancer, or if a man is at a higher risk for developing breast and prostate cancer.
“It really is most relevant for individuals with Ashkenazi Jewish background because it can only look at three variants that can occur in these genes, when there are thousands possible,” Frone says.
The actual test has been put in the Medical Devices class II risk category by the FDA. Class I devices, such as dental floss, are lowest risk. Class II, which includes condoms and powered wheelchairs, are moderate risk. Class III devices, such as pacemakers, require FDA approval in order to be marketed, while class I and II do not.
These mutations “are most common in people of Ashkenazi Jewish descent and do not represent the majority of the BRCA1/BRCA2 variants in the general population,” the FDA cautions.
Researchers estimate that roughly 5-10 percent of all cancers have a known genetic element, so while DNA tells a story, it doesn’t write the entire script. External factors, like environmental nutrients or toxins, and lifestyle choices also influence risk for developing cancer.
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