Things You Should Know About At-Home Genetic Tests for Cancer
Updated December 7, 2020
Nowadays, looking into “what makes you, you” takes as little as six weeks. At home DNA tests can provide valuable insight into your risk for certain diseases, including some cancers, but these tests aren’t foolproof, and the results may not tell the full story of how your genes could affect your health.
Michael J. Hall, MD, MS, Chair and Professor in the Department of Clinical Genetics, sheds light on some of the most pressing questions about at-home genetic tests.
1. What is at-home, or direct-to-consumer (DTC), genetic testing?
There are a number of DTC test kits you can order without a doctor’s prescription that offer personalized genetic analyses (ranging from ancestry to health risks).
The health tests may tell you what your risk for a certain disease is, such as cancer or Alzheimer’s. However, it is important to remember that DTC tests detect genetic markers that may increase disease risk, but being at risk for a disease does not mean you will ever get it.
2. Are DTC tests a good place to start for patients concerned about cancer?
“Conducting DTC tests to learn more about your ancestry can provide fun, interesting information,” Hall said. “My concern is with predictive tests for medical issues. It is optimal for patients receiving medical information to also receive genetic counseling, or at least have a physician oversee the process.”
DTC tests might not be able to provide the full picture of a patient’s risk. Several other factors, such as lifestyle choices and family history, can affect disease risk as well.
While DTC tests may seem like a good option, it is recommended that individuals with a true concern for their cancer risk and those looking for guidance meet with a medical professional.
3. Are there benefits to DTC genetic testing?
DTC tests can raise public awareness about genetic information. Some tests can be ordered in partnership with a doctor and may provide a way for people to get screened if they live far away from a testing center, cannot afford formal testing, or get denied coverage for screening because they don’t have a family history of disease.
4. What are the downsides of DTC genetic testing?
“We tend to focus on the things we are interested in that are congruent with our existing beliefs,” Hall said. “If you are unaware of certain risks in your family, you may scan the results, quickly dismissing some while being overly concerned about others. People might see that they have a high lifetime risk of a certain cancer and feel alarmed, whereas if they saw a genetic counselor, they would know there are ways to substantially mitigate the risk and potentially never get that disease.”
It is best to avoid over-interpreting the reams of raw data DTC companies send you. An article in Genetics in Medicine found that 40 percent of variants in genes reported in DTC raw data were false positives. Certain common genetic variants were also misclassified as being associated with increased risk.
Some DTC testing may only look at specific genetic changes instead of the comprehensive analysis done during clinical diagnostic testing, so it is possible you carry a harmful genetic trait that would not be identified in the DTC test. Positive results are also not typically confirmed with a “double-check” test, which is recommended in clinical genetic testing labs.
5. What’s different about going to a genetic counselor instead of taking a DTC genetic test?
Genetic counselors go through medical and family history to make sure testing is clinically appropriate for each patient. For some patients, everything looks great and they do not need testing; but patients who have a family history of cancer or have other risk factors will get a full assessment.
Before deciding on the best testing path for a patient, genetic counselors explain the potential benefits and limitations of testing so individuals can make informed decisions about their options.
Being at risk for a certain type of cancer does not mean you have or will ever get it.
6. What can a genetic counselor do for patients?
“We want people to talk to a genetic counselor before and after they get screened, so they know what they are getting into, what the results mean, and what to do next,” Hall said.
One of the biggest benefits of seeing a genetic counselor is having somebody to advocate for you. They will make sure you are basing decisions on good information, will answer all of your questions, and even help with logistics (such as checking insurance coverage and figuring out which lab to use for testing).
7. What does Fox Chase offer that does not come with DTC testing for cancer risk?
“There are advantages to coming to Fox Chase rather than doing at-home genetic testing,” Hall said. “For patients who have a genetic risk, we can discuss screening, prevention, and treatment options that may benefit them. We can guide patients who need treatment to new therapeutic targets that may lead to clinical trials.”
The clinicians at Fox Chase will also help patients’ family members get screened, if appropriate. We offer family planning for anyone concerned about passing on certain genetic risks to their children, and social services are also available for patients who feel overwhelmed or distressed by their results.
At Fox Chase, we give patients the resources to make the right decisions for themselves and their families.
8. What if you take a DTC genetic test and then have questions?
“If you take a test at home, call our genetic counseling program so someone can walk you through the results,” Hall emphasized. “This is really important to understand if you actually have a risk of cancer. Patients and doctors alike can misinterpret genetic results, and our biggest task is to educate people on what the test results mean and their next steps.”
9. What is all the buzz about DTC testing for BRCA1 and BRCA2 gene mutations?
While DTC tests may seem like an appealing option to find out if you have mutations in these genes, some of these tests only address a few specific BRCA1/BRCA2 gene mutations out of more than 1,000 known mutations.
For example, some only test for the most common mutations in people of Ashkenazi Jewish descent, which are not common BRCA1/BRCA2 mutations in the general population.
While these tests are not ideal, there is one positive thing about them.
“The positive side to this DTC test is that it can raise awareness about BRCA mutations for both women and men,” Hall said. “Many people do not realize that BRCA genes are predictive of prostate and other cancers in men. In fact, the national guidelines recommend BRCA testing for metastatic prostate cancer.”
If you remember one thing, remember this: Having a risk of developing cancer doesn’t mean you will ever get it. If you take a test at home, call the Fox Chase Risk Assessment Program to talk to someone who can walk you through the results. If you have concerns about cancer risk, let our genetic counselors help.
Find out more about the Risk Assessment Program at Fox Chase.
Updates were reviewed by Catie Neumann, MS, LCGC, genetic counselor at Fox Chase Cancer Center.