Cancer is a top cause of death globally, which makes cancer prevention a vitally important public and personal health priority. Researchers estimate that 5-10% of cancers are caused by inherited mutations, and there have been more than 50 hereditary cancer syndromes discovered, with more sure to come.[3]
But direct-to-consumer genetic testing can leave patients confused, scared, or overwhelmed and unsure how to proceed. For National Cancer Awareness Month, learn more about the world of direct-to-consumer genetic testing. If and when patients come to you with questions about their genetic testing results, here is a roadmap for the conversation.
Direct-to-consumer genetic tests have been found to have quality issues. Talk to your patients about these issues. An NBC station sent human and dog DNA samples to several genetic testing companies. Worryingly, one company responded with a full genetic analysis of the Labrador retriever, as if it were a human.[4] This is obviously an extreme example, and companies that offer screening for cancer genetics are more highly regulated by the FDA and are far less likely to encounter these issues. But patients should be aware of quality issues within the industry.
The science is rapidly changing, and much is still unknown. The field of genomics is staggeringly complex, very new, and rapidly changing. Some direct-to-consumer genetic testing companies may overstate the impact of certain findings, especially in regards to nutrition and athleticism.[5]
Carrying a mutation is not necessarily a guarantee of illness. It is true that some genes are tightly bound with disease, such as how mutations in the BRCA1 or BRCA2 genes dramatically increase a risk of breast cancer. But many other links between mutation and illness are less strong.[6] And even when a mutation clearly increases risk of a disease, remind patients that while their relative risk may be higher, their absolute risk may still remain low. In other words, a hypothetical mutation may double a patient’s risk of a certain rare disease. But if the original risk is 1 in 10,000, the doubled risk becomes 1 in 5000—a far more reassuring statistic.[7]
When in doubt, refer out. Unless you are a trained genetic counselor, you are likely unprepared to give counsel to patients about their results. The field of genetic testing is far too complex for most health care professionals to learn on their own. A good rule of thumb, recommended by the American Medical Association, is to know what you don’t know and be honest.[8] This may mean referring patients to genetic counselors, or for further testing.
The best way to prevent cancer is through lifestyle changes. Diet, weight, exercise, sun exposure, tobacco usage, and regular medical care play a huge role in cancer. Counsel your patients to eat a healthy diet high in fruits, vegetables, nuts, and legumes, and low in refined sugars, animal fats, and processed meats. Patients should aim for 150 minutes a week of moderate exercise. If your patients smoke cigarettes, quitting is critical to their health. Encourage patients to reduce sun exposure, get HPV and Hepatitis B vaccines, and have regular medical screenings.[9]
Armed with this knowledge, you can help your patients reduce their cancer risk and navigate the complex world of genetic testing!
References:
[1] https://blogs.cdc.gov/genomics/2018/06/12/consumer-genetic-testing/
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3255226/
[3] https://www.cancer.gov/about-cancer/causes-prevention/genetics/genetic-testing-fact-sheet
[4]https://www.nbcchicago.com/investigations/home-dna-kits-481292431.html
[5] https://www.ama-assn.org/delivering-care/precision-medicine/what-your-patients-must-know-about-direct-consumer-lab-tests
[6] https://ghr.nlm.nih.gov/primer/mutationsanddisorders/predisposition
[7] https://cpmc.coriell.org/genetic-education/understanding-risk
[8] https://journalofethics.ama-assn.org/article/how-should-primary-care-physicians-respond-direct-consumer-genetic-test-results/2018-09
[9] https://www.mayoclinic.org/healthy-lifestyle/adult-health/in-depth/art-20044816