Guideline: FDA approves at-home test kits for inherited cancer: how useful are they?


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People who are considering or have had direct-to-consumer testing through 23andMe

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Checked Healthy people with average cancer risk

Checked Her2+ breast cancer

Checked Men with breast cancer

Checked People with a genetic mutation linked to cancer risk

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Checked Triple negative breast cancer

Checked Women under 45

Checked Women over 45

Checked Special populations: Men and women of Ashkenazi Jewish descent. People who are considering 23andMe testing.


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Interest in personalized genetic testing is growing. Genetic testing about health conditions typically requires a prescription from a health care provider. Until recently, the direct-to-consumer (DTC) testing market has focused on ancestry and discovery of unknown branches of family trees. A laboratory called 23andMe that provides direct-to-consumer genetic testing has been given FDA approval to report results for 3 mutations found in the BRCA1 and BRCA2 genes. The FDA statement provides details about this approval and cautions consumers about the limitations of the 23andMe test. (03/19/18)

Contents

Direct-to-consumer testing What does this mean for me?
Risks of DTC testing                                      Guidelines                                              
Benefits of test Resources and references
Testing without healthcare professionals  


What is direct-to-consumer genetic testing?

Testing for genetic mutations that raise the risk for disease has historically required a prescription from a health care provider. The FDA recently approved the first direct-to-consumer (DTC) test for 3 specific mutations in the BRCA genes, which have been linked to increased risk for breast, ovarian, and other cancers. Consumers collect a saliva sample, send it directly to the 23andMe lab for testing, and receive their genetic results without involving a health care provider.

What are the risks of the 23andMe direct-to-consumer genetic test? 

  • The National Comprehensive Cancer Network (NCCN) sets national, expert standard-of-care guidelines for cancer care. NCCN recommends that people consult with a genetics professional before and after genetic testing. By circumventing the need to consult a health care professional, DTC genetic testing falls below standard-of-care.
  • The 23andMe test is an incomplete test for cancer risk.
    • The test identifies whether a person carries any of 3 specific mutations in BRCA genes (BRCA 185delAG, BRCA1 5382insC or BRCA2 6174delT). These mutations found most frequently in people of Ashkenazi (Eastern European) Jewish descent. For people who test positive for a mutation, the 23andMe test provides important information about their risk for cancer. But for people who test negative, the test does not provide much information about cancer risk.
    • The FDA approval statement notes that 1,000 other BRCA mutations also increase cancer risk. Technically, this is accurate, but it is a dramatic understatement. To date, over 5,400 different BRCA mutations (2,549 in BRCA1 and 2,941 in BRCA2) that can increase cancer risk have been identified.
    • Over 27 genes have been linked to increased risk for hereditary breast, ovarian and other cancers. Mutations in other genes, such as CHEK2, ATM and PALB2 and others also increase cancer risk. So, a person whose 23andMe test is negative for a mutation may still have a different mutation in BRCA1 or BRCA2 or another gene that significantly increases cancer risk. 
    • The FDA report fails to mention that more complete tests are available to help people understand their cancer risk. Tests are available that look for the thousands of other BRCA mutations as well as mutations in other genes which are not detected by the 23andMe test. The cost for these tests are often covered by insurance and low-cost options may be available.
    • Individuals who receive a negative test result from 23andMe may have a false sense of confidence about their cancer risk. As the FDA cautions: “The test should not be used as a substitute for seeing your doctor for cancer screenings or counseling on genetic and lifestyle factors that can increase or decrease cancer risk.” 

Who can benefit the most from this test?

People of Ashkenazi Jewish descent who have never had BRCA testing will have the most benefit from the 23andMe test. About 2% of all Ashkenazi Jewish people—regardless of personal or family history of cancer—will carry one of the 3 mutations in the 23andMe test.

However, even Ashkenazi Jewish people can have a mutation in one of the over 5,000 other BRCA mutations, or in another gene like CHEK2, ATM or PALB2.  One study showed that among Jewish women with breast cancer, 0.8% have other BRCA mutations and 3 to 4% carry a mutation in another breast cancer gene (see our prior XRAY Does expanded genetic testing benefit Jewish women diagnosed with breast cancer?) These mutations are not detected in the 23andMe test. Therefore, negative results among Ashkenazi Jewish individuals are not conclusive either.

This new 23andMe DTC test has very limited usefulness for the general population. The test may benefit those who are unaware of their Jewish ethnicity and who test positive for one of the 3 mutations.

Healthcare professionals are not involved in the new 23andMe test

In DTC testing no medical or genetic counseling is included. Test results are returned electronically with a written explanation. Further questions and discussion of follow-up testing or treatment options are not included. As the FDA notes, this testing cannot be used to determine treatment without retesting and consultation: “Consumers and health care professionals should not use the test results to determine any treatments, including anti-hormone therapies and prophylactic removal of the breasts or ovaries. Such decisions require confirmatory testing and genetic counseling. The test also does not provide information on a person’s overall risk of developing any type of cancer. The use of the test carries significant risks if individuals use the test results without consulting a physician or genetic counselor.”

The FDA examined how the test is performed and assures consumers that the test is accurate and reliable. The agency also warns that consumers must be careful about what this test does and does not tell them. They caution that without a provider explaining the nuances of the results, misunderstandings may occur.  Many genetics experts concur and believe that the issue with DTC testing is that education and informed decision-making is best done in the clinical setting in consultation with medical professionals.

What does this mean for me?

This test can check your DNA for 3 specific BRCA mutations. Negative results convey very limited information and are likely to be confusing to a consumer without support of a genetics expert. Positive results are more conclusive and provide valuable information for preventative screening and treatment considerations. However, because this testing is done without medical oversight consumers should be aware of these important considerations:

Your health care provider will be aware of your result only if you share them.
Consumers with a positive results might incur additional costs (dependent on individual insurance coverage) associated with clinical confirmation of the test results and follow-up genetic counseling and medical visits. 23andMe does not provide follow-up testing.

For most consumers, the actual benefit of this test will be through subsequent genetic counseling and follow-up with health care providers.  Finally, it is important to understand that even if you are of Ashkenazi Jewish decent, you may have a mutation in BRCA1, 2 or other genes that are not included in this test.

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Expert Guidelines

At the present time, this approval does not lead to any changes in recommendations for genetic counseling and testing. The National Comprehensive Cancer Network is a consortium of experts in cancer and genetics. They publish consensus guidelines for genetic counseling and testing for cancer risk.

  • According to NCCN, cancer risk assessment and genetic counseling is highly recommended before genetic testing is offered (pre-test counseling) and after results are disclosed (post-test counseling). A genetic counselor, medical geneticist, oncologist, surgeon, oncology nurse, or other health professional with expertise and experience in cancer genetics should be involved early in the counseling of patients.
  • NCCN cautions about genetic testing through companies that provide ancestry testing (such as 23andMe). Commercial entities providing ancestry (and sometimes health) information typically do so through a type of testing known as “SNP-based testing”. This testing has not been validated for clinical use. Research suggests that the error rate for these tests may be substantial.

In their approval, the FDA make the following notes about test results through 23andMe:

  • Consumers and health care professionals should not use the test results to determine any treatments, including anti-hormone therapies and prophylactic removal of the breasts or ovaries. Such decisions require confirmatory testing and genetic counseling.
  • The test also does not provide information on a person’s overall risk of developing any type of cancer. The use of the test carries significant risks if individuals use the test results without consulting a physician or genetic counselor.
  • The test only detects three out of more than 1,000 known BRCA mutations (the three most common in people of Ashkenazi Jewish ancestry). This means a negative result does not rule out the possibility that an individual carries other BRCA mutations that increase cancer risk. All individuals, whether they are of Ashkenazi Jewish descent or not, may have other mutations in BRCA1 or BRCA2 genes, or other cancer-related gene mutations that are not detected by this test. For this reason, a negative test result could still mean that a person has an increased risk of cancer due to gene mutations. 

Questions To Ask Your Health Care Provider

  • Given my personal and family history, will this test be informative?
  • Are there other options for genetic testing? How do they compare to this test?
  • If I test negative, should I consider further genetic testing?
  • If I test positive, what is my cancer risk? What preventative measures could I consider? Should I consider different treatment options?
  • Should I share my 23andMe results with my relatives? Which ones?
  • Can you refer me to a genetic counselor?

Media Coverage 

After this report was published by the FDA, a large number of media sources covered it. This includes NBC News which published “FDA OKs 23andMe home breast cancer DNA test, with warning," containing a misleading graphic. FORCE covered the article in a recent Headline Hype blog post.  

Conclusions:

This direct-to-consumer test is a reliable way to identify 3 specific BRCA mutations. Individuals who test negative may carry one of thousands of other mutations in BRCA1 or 2 or in a breast cancer gene that is not included in this test. Consumers may underestimate their risk of breast cancer and other cancers associated with these mutations, including ovarian cancer in women and prostate cancer in men.

For additional information read FORCE advisor board member and 2018 Spirit of Empowerment awardee Dr. Susan Domchek’s piece "At-home genetic testing may be convenient, but it isn’t complete" in Stat News.

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Posted 3/19/18

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