Clinical vs. DTC Genetic Testing

When 23andMe laid off roughly 100 employees last month, it was another admission that direct-to-consumer, or at-home, genetic testing sales are down at some leading companies. The reasons, however, while varied, have nothing to do with the interest in genetic testing. People want the information but it seems many prefer to get it from their doctors.

Theres reason for the interest: The field of genetics is booming.

Since the 1990s when we started testing for BRCA1, BRCA2 [which most notably increase the risk of breastandovarian cancers]and TP53 [which regulates cell division and keeps tumors from forming], the number of indications, or signs for cancer and the number of genes we can identify has expanded. And it will only continue to grow, Dr. Banu Arun, co-medical director of the Clinical Cancer Genetics Program at MD Anderson Cancer Center, tells SurvivorNet.

She notes that clinical genetic tests can aid in making recommendations for surveillance, determine prognosis and assist in treatment decision-making for cancer patients. Direct-to-consumer genetic tests dont offer that proverbial microscope.

When trying to understand your hereditary cancer risk, saysDr. Arun, clinical testing is the way to go.

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 peoples health and ancestry. But theyre limited when it comes to offering tests for cancer risk. Currently, theFood 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 BRCA1andBRCA2.

With direct-to-consumer testing, its 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. Theyre only looking at three pages, she says. You could have a typo anywhere else in the novel thats breaking that gene and giving you a higher risk for cancer, and theyre just not looking.

Clinical-grade testing can analyze the risk of 50 different types of cancer, according to The National Cancer Institute.

A study last year from the National Center for Biotechnology Informationnotes some other drawbacks, including how DTC tests frequently do notprovide 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 dont have any particular treatment for Alzheimers. Some people dont want to know about that stuff because theres nothing they can do about it. They dont necessarily realize that theyre 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 theCenters for Disease Control.

A recent study based on anonline survey of 1,001 adultsrepresentative 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.

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, theyll look at personal medical history and family medical history. And, if youre female, theyll look at your hormonal risk factors, Frone explains. There are computer models to identify risks and patterns within someones 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, weve 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. Its 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 doesnt write the entire script. External factors, like environmental nutrients or toxins, and lifestyle choices also influence risk for developing cancer.

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Kim Constantinesco is a freelance writer who specializes in health and founder ofPurpose2Play, which reports on positive and inspiring stories in sports. Read More

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Genetic Testing Is on the Rise Heres Why to Get it Done Through a Health Care Provider - SurvivorNet