What to Know About At-Home DNA Tests for Detecting Cancer Risk

May 24, 2022
ASCO Staff

You might have seen or heard about at-home DNA tests that claim to identify your health risks. Doing a quick internet search for “at-home DNA tests” will bring up dozens of companies offering these services.

Many of these companies offer DNA tests that describe your genealogy and offer insights into your race and ethnicity. But some companies offer DNA tests to find out if you are more likely to develop certain diseases. Sometimes, these tests are offered together as part of a package describing both your ancestry and your health risks.

But what can these tests tell you about your risk for cancer, and what should you consider if you’re thinking about buying one? Here, learn what these tests are, how they work, and why it’s always better to get genetic testing done through your health care provider. 

What are at-home DNA tests, and how do they work?

At-home DNA tests, which are also called direct-to-consumer DNA tests, are tests that people can take at home to predict their genetic risk for certain diseases. They work by testing your DNA for variants in your genes that are linked to some diseases. At-home DNA tests differ from most genetic testing, which is facilitated by a doctor or genetic counselor. When genetic testing is facilitated by your health care provider, you and your health care provider both receive the results and then discuss them together.

With at-home DNA tests, however, you work directly with a private company instead of your health care provider. You pay for the service out of your own pocket in advance. Typically, the service sends a kit that directs you how to collect and mail back a sample of your saliva so it can be tested at a private company’s lab. The lab studies the DNA contained in your saliva. Then, the company sends you a report about your DNA results, or you’ll be sent instructions on how to log onto a website to see the results.

Some direct-to-consumer DNA tests say they can predict your risk for certain types of diseases, such as diabetes, eye disease, celiac disease, late-onset Alzheimer’s disease, or some types of cancer. However, it is important to remember that these predictions are just one part of your risk profile. Your genes are just one of many factors that contributes to your risk for disease. Other factors that influence your risk for diseases include your environment, age, lifestyle, and more. At-home DNA tests cannot offer definitive answers, and they may trigger more uncertainty about your health.

Always talk with your health care team first if you are interested in receiving genetic testing. They can guide you on the tests that are most appropriate for you based on your individual risk factors.

“There are many nuances about cancer genetic testing, since laboratories offer various options of cancer gene panels and the methodology to detect gene variants may also differ. As such, it is challenging for someone to fully know if the test they are seriously thinking about taking is appropriate and comprehensive based on their personal and family medical history. I can’t emphasize enough the importance for someone to talk with their doctor or a genetics expert like a genetic counselor about the process of genetic testing and the implications of the results for themselves and their family members.” – Mercy Laurino, MS, CGC, PhD, director of the Seattle Cancer Care Alliance’s Genetics and Prevention programs and an advisory panelist on the 2022 Cancer.Net Editorial Board

What can at-home tests tell you about your risk for cancer?

For the general population, direct-to-consumer DNA tests for cancer risk are extremely limited. There is only 1 direct-to-consumer test that has approval from the U.S. Food and Drug Administration (FDA) to report on 3 gene variants, or mutations, that can help predict a person’s increased risk for breast cancer, ovarian cancer, or prostate cancer. These variants occur on the BRCA1 and BRCA2 genes and are 3 of thousands of known variants associated with an increased risk for cancer.

These 3 variants are more common in people of Ashkenazi Jewish ancestry, but they are not the most common variants overall in the general population. They occur in about 2% of Ashkenazi Jewish women, according to a study by the National Cancer Institute.

It is important to remember that if you receive a negative result on this test, it does not necessarily mean your cancer risk is low because the test only reports on 3 variants. In fact, most people will probably receive a negative result, according to the National Library of Medicine. Many other variations in the BRCA1 and BRCA2 genes that are not detected by this test could increase your risk for breast, ovarian, or prostate cancers. Because of this, you should not rely on an at-home test to predict your cancer risk.

There are, however, certain types of at-home tests that your doctor may recommend for cancer detection, including a type of stool test called a fecal occult blood test (FOBT) that screens for colorectal cancer. FOBTs test your stool for the presence of blood, which may be a sign of colorectal cancer. These tests are different from those that test your genes for variants that could increase your risk for cancer. Ask your doctor about the most appropriate cancer screening tests for you.

What else should I consider before taking an at-home test?

You should consider the privacy concerns in submitting a DNA sample to a private company for analysis before you sign up. For example, do they sell your data to third parties? Are they subject to the same Health Insurance Portability and Accountability Act (HIPAA) rules to protect your privacy as tests done in your doctor’s or genetic counselor’s office? These are all important factors to investigate before taking an at-home DNA test with any private company.

What should you do if you receive a positive result on at at-home test?

If you receive a positive result from a direct-to-consumer DNA test, always talk with your doctor about the result. They can help you interpret the findings and decide whether you need further testing or other options to consider. Even if your result is negative, if you are concerned about your personal and family history of cancer, talk with your doctor to ensure you receive a comprehensive cancer risk assessment.

Your doctor can also refer you to a genetic counselor, or you can schedule an appointment with a genetic counselor on your own. Genetic counselors are health care professionals trained to help people and their families understand how their genetics influence their risk for disease. They help you choose the appropriate genetic tests for you and help you navigate the questions that genetic testing can bring up. You can find a genetic counselor through the directory at the National Society of Genetic Counselors website.

Genetic testing for cancer plays an important part in cancer diagnosis and treatment. It can tell doctors who is at high risk for disease and who may benefit most from earlier cancer screening or treatment with certain drugs. Right now, at-home DNA tests for cancer risk are limited in what they can tell you and who they can help most. So if you are concerned about your cancer risk, talk with your doctor first.

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