Understanding Direct-to-Consumer Genetic Testing, with Nadine Tung, MD

October 27, 2016
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In today’s podcast, we will discuss direct-to-consumer genetic testing. You may have seen these at-home genetic testing kits advertised on television or the internet. Genetic testing can be used to estimate a person's risk of developing specific diseases, such as cancer. However, direct-to-consumer genetic testing may have significant limitations, and the decision to be tested for cancer risk is complex. This podcast will be led by Dr. Nadine Tung, the Director of the Cancer Risk and Prevention Program at Beth Israel Deaconess Medical Center. 

Transcript: 

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ASCO: You're listening to a podcast from Lineagotica. This cancer information website is produced by the American Society of Clinical Oncology, known as ASCO, the world's leading professional organization for doctors who care for people with cancer.

In today's podcast, we will discuss direct-to-consumer genetic testing. You may have seen these at-home genetic testing kits advertised on television or the Internet. Genetic testing can be used to estimate a person's risk of developing specific diseases, such as cancer. However, direct-to-consumer genetic testing may have significant limitations, and the decision to be tested for cancer risk is complex. This podcast will be led by Dr. Nadine Tung, the Director of the Cancer Risk and Prevention Program at Beth Israel Deaconess Medical Center.

ASCO would like to thank Dr. Tung for discussing this topic.

Dr. Tung: My name is Dr. Nadine Tung. I am a medical oncologist at Beth Israel Deaconess Medical Center in Boston. I care for women with breast cancer and also for individuals, with and without cancer, who have a lot of cancer in their families. I oversee the genetic testing at Beth Israel Deaconess Medical Center for genes that cause an inherited risk of cancer. Today, I'm going talk to you about direct-to-consumer genetic tests. So let's start with what is a direct-to-consumer genetic test and how does it work. I always like to start by clarifying that genes are the information, or the instructions, that we inherit from our parents that dictate many things such as our physical features, but also sometimes our risk of developing certain diseases including cancer. This inherited information is stored in our genetic material also known as genes or DNA.

So genetic tests examine our genes to see if there are changes that might indicate and increase risk of diseases such as cancer, or even if we might react to certain drugs or toxins in a certain way. The genetic test might look at one or two changes in our genes or a million changes. Some genetic changes are known to increase the risk of disease a lot, maybe tenfold, while other genetic changes have much less impact on our risk for disease and may not even double the risk of that disease. These less risky genetic changes are what are typically being measured in direct-to-consumer genetic tests, and as such are really like many other risk factors that exist for a disease, perhaps comparable to a cholesterol level for the risk of heart disease, or comparable to whether a woman nursed her children when considering breast cancer risk.

For the most part, direct-to-consumer genetic tests are not measuring the same genes that are being tested through high-risk genetic clinics and hospitals, tests that are ordered by doctors. Those genetic tests evaluate genes such as BRCA1 and BRCA2, genes for which inherited abnormalities confer a very high risk of breast cancer, ovarian, and other cancers. That is not typically what we are discussing when we talk about the changes being analyzed in direct-to-consumer genetic tests. Typically, direct-to-consumer tests require a cheek swab or a sample of saliva and are collected at home and sent directly to a company. No physician prescription is required. The price of these direct-to-consumer genetic tests can range from less than a hundred dollars to a few thousand dollars.

Next, let's discuss the advantages and disadvantages of these direct-to-consumer genetic tests. Well, are there any advantages? I think the only advantage, maybe that it can be done from home and perhaps it may satisfy some curiosity in individuals about their risk of certain illnesses, but there are far more potential disadvantages of these direct-to-consumer genetic tests, and the drawbacks really outweigh advantages.

So what are these disadvantages? Well first, often a consumer may not even realize which genes are being analyzed. As mentioned, while most of the genetic changes being analyzed are less risky, sometimes more significant genetic changes are also being analyzed, such as the BRCA1 and the BRCA2 genes we talked about earlier. If the consumer is not aware or prepared for the results, this can be confusing and create anxiety. If more significant high-risk genes like BRCA1 and 2 are being are being tested, an individual should really have counseling before the test is performed. Counseling by a healthcare provider with knowledge in the genetic field in order to really prepare someone for what a possible genetic change might mean both for their own health and for their family. So testing for high-risk genes should not be done lightly without counseling. That's first. What other disadvantages exist with these direct-to-consumer genetic tests? Well, genetic test results can be complex to interpret. Even genetic specialists may not fully understand the results of all changes. Results may not always be obviously normal or abnormal. Sometimes the result is unclear, so having a specialist to help interpret results is crucial.

In addition, interpreting how a genetic test result contributes to an individual's risk of disease should really be done in the context of all the other risk factors since the genetic change is only one component of that risk. Most of the time, the risk for any disease, whether it's cancer or heart disease, is the result of an interaction between an inherited risk but also environmental exposures, and that interaction can be very complex. Therefore, genetic results are often only one piece of information regarding an individual's risk of disease. Family history, a person's medical history, again, environmental exposures, lifestyle choices all play significant roles when assessing a person's risk of disease. Therefore, understanding how a particular genetic change alone contributes to the risk of disease may not be clear. For example, even if a genetic test is normal, if an individual has a strong family history for a certain disease, that person may still have a significant risk for the disease even if the genetic test is normal. Another drawback of direct-to-consumer genetic tests is that there has been concern about the accuracy of these tests and the reliability of the tests. Sometimes a person's results differ from one company to another. In addition, there's been some question about whether the changes found indeed do increase the risk of disease and to the extent that the companies claim. Often more studies are needed to really feel certain that the companies' claims are true with regard to predicting the risk of disease.

So, what should one consider before buying or using these tests? First, consumers should know that they are not FDA approved. Other home-use medical tests such as pregnancy tests undergo FDA review for both safety and efficacy, but the FDA has not authorized any direct-to-consumer genetic test. What else should someone consider before using these tests? Well, as mentioned earlier, pre-test counseling should really be performed before any genetic test is ordered. How will this test affect knowledge about my own risk of disease? How will it affect my family? Will it prevent my being able to obtain life or other insurance? Exactly which genes are being analyzed, and what can I truly learn about my health from the results? These are all questions that should be considered before genetic testing is performed. Individuals considering a direct-to-consumer genetic test should also consider issues about privacy and protecting their privacy. Consumers should read the privacy policy of the company and understand how the company will protect their privacy. How will the company use the information or share their information with third parties?

So in summary, consumers should understand the potential benefits and limits of the test before purchasing. Consumers should talk to their doctor or healthcare provider about whether the genetic test will provide useful information and if so, which test to order. Genetic testing is best done with your healthcare provider who will be able to interpret the results and to comment how this genetic result contributes to your overall risk of disease. It's important to remember that direct-to-consumer genetic testing is not a substitute for traditional healthcare evaluation. And finally, if an individual is concerned about a result that they received from a direct-to-consumer genetic test, what should they do? Well, they should talk to their physician or their healthcare provider or a genetic specialist about how to interpret the results. That provider can help clarify how the genetic result fits into their overall risk of developing a disease, again, given the other known risk factors. Thank you so much.

ASCO: Thank you Dr. Tung. Additional information about the genetics of cancer and genetic testing can be found at lineagotica.info/genetics. And for more expert interviews and stories from people living with cancer, visit the Lineagotica Blog at lineagotica.info/blog.

Lineagotica is supported by the Conquer Cancer Foundation, which is working to create a world free from the fear of cancer by funding breakthrough research, sharing knowledge with physicians and patients worldwide, and supporting initiatives to ensure that all people have access to high-quality cancer care. Thank you for listening to this Lineagotica podcast.

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