Earlier this year, the Food and Drug Administration made news by approving a direct-to-consumer (DTC) genetic testing option for hereditary breast and ovarian cancer (HBOC) syndrome through 23andMe, wherein testing can be ordered directly by individuals without the involvement of a health care provider (U.S. Food & Drug Administration, 2018). Although there are some caveats to the testing, this decision marks a turning point in the individual's access to clinically relevant genomic information outside of the medical setting. In honor of breast cancer awareness month, this month's column provides some tips for understanding and using the results of DTC genetic testing for the BRCA1 and BRCA2 genes.
Consider the following two patients, who have both recently chosen to receive results about their breast cancer risk through a DTC testing (or “personal genomics”) company.
- Beth, 53, has received results that indicate she does not carry any of the mutations related to HBOC tested by the company. She feels relieved because her mother and aunt both had breast cancer under the age of 50 and her sister recently died from ovarian cancer in her early 50s.
- Gina, 31, received results that indicate she has a mutation that puts her at a much higher risk for developing breast and ovarian cancer. She is very surprised because no one in her family has had cancer. She is not sure whether she should believe the results.
These cases highlight some important benefits and limitations of BRCA1/2 testing available DTC.
Before using DTC test results (positive or negative) to make clinical decisions, results need to be confirmed in a clinical laboratory on a new sample
There is a small chance that the result of the DTC methods used can be false-positive or false-negative, so it is important to confirm the result on a fresh blood sample (FDA, 2018). Genetic experts can help determine the appropriate testing to confirm the results, as well as evaluate personal and family history to determine level of risk and whether additional testing is needed.
Negative results on DTC testing are not definitive; additional testing may be needed if there is a clinical indication of higher risk
Beth was reassured by her negative results on BRCA1/2 testing. Unfortunately, this feeling of reassurance is inappropriate. The test she received assessed for only three of the thousands of mutations in these genes known to be associated with HBOC syndrome. Although she can be reassured that she does not have one of the three mutations tested, these results do not reduce her risk significantly. Because testing was not sufficient to assess her risk, she remains at the high risk indicated by her family history.
Clinical evaluation and testing for HBOC typically starts with assessing a detailed family history to determine the level of risk and appropriateness for testing. With someone who has already had some testing, like Beth, it is important that the provider review the report to determine what testing has been done and whether it assesses the appropriate variants. Depending on the situation, an individual may need to be tested for a panel of 20 or more genes or, if the mutation causing cancer in the family is known, a single mutation. Given Beth's strong family history of breast and ovarian cancer, additional genetic testing is likely needed to determine whether she is at high risk of developing cancer. She should talk with a genetics expert to further clarify her risk and discuss whether and how to proceed with additional genetic testing (Table 1).
Positive results on DTC testing can help identify individuals who did not know they were at risk
Gina was surprised by her positive results on BRCA1/2 testing, especially because she did not know of anyone in her family that had been diagnosed with cancer. Not everybody with HBOC has a strong family history of breast and/or ovarian cancer, which is typically what is warranted to get genetic testing ordered by a clinician. People may have small families, not talk with all or certain relatives about health issues, or be adopted. In these cases, there may not be enough information to determine if someone is at increased genetic risk.
Receiving a positive result, either expected or unexpected, provides the opportunity to take action to identify cancer early and reduce risk. All clinically relevant results from DTC testing need to be confirmed in a clinical laboratory before taking any action. Once confirmed, there are clinical guidelines for increased cancer screening and options to reduce risk that patients can follow (National Comprehensive Cancer Network [NCCN], 2018). Genetic experts can help in the process of confirming results and outline screening and risk reduction options.
Next steps after DTC testing
If a patient like Beth or Gina presents in clinic with questions about a DTC genetic test for breast cancer risk, review the test result to determine what was included in the analysis and the laboratory's interpretation. Talk with the patient about the importance of confirming DTC test results (positive or negative) in a clinical laboratory if the results are to be used for clinical decision making. Consider referring such patients to a genetic expert, such as a medical geneticist, genetic counselor, or other health care provider with specialized genetic training, to assist in comprehensive breast cancer risk assessment, genetic testing results interpretation, coordination of confirmatory testing, and management of high-risk individuals (Table 1). There are also educational resources that provide ways to learn more about DTC testing and breast cancer genetics (Table 2).
Acknowledgements:An earlier version of this article was previously published on the The Jackson Laboratory website.
National Comprehensive Cancer Network (NCCN). (2018, July 30). NCCN clinical practice guidelines in oncology, genetic/familial high-risk assessment: breast and ovarian, version 2.2019. Retrieved from http://www.nccn.org
U.S. Food & Drug Administration (FDA). (2018, March 6). FDA authorizes, with special controls, direct-to-consumer
test that reports three mutations in the BRCA breast cancer
genes [press release]. Retrieved from https://www.fda.gov/newsevents/newsroom/pressannouncements/ucm599560.htm