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Listen to the podcast companion to this feature: ASCO's Policy Statement Update on genetic Testing for Cancer Susceptibility, with Kenneth Offit, MD, MPH
You may have seen tests advertised on the Internet or elsewhere that can be used to check your risk for specific diseases, including cancer, at home. These tests are called direct-to-consumer (DTC) genetic tests. ASCO recently updated its 2003 recommendations for genetic testing to include information on DTC testing, as well as to provide advice to doctors and patients on some of the newer technologies becoming available for cancer screening. To learn about these tests and how to talk with your doctor about genetic testing, Cancer.Net talked with Kenneth Offit, MD, MPH. Read ASCO's updated genetic testing recommendations.
Q: What are DTC genetic tests? How are they used?
A: DTC genetic tests fall into two categories:
First are DTC tests for genetic mutations (changes) of known clinical significance. These tests include mutations in genes (such as those for hereditary breast, ovarian, and colon cancer) for which there are accepted screening and prevention guidelines if such a familial cancer risk is detected.
The second type of DTC tests is for gene changes (called variants), where the low level of risk for cancer may not lead to any specific medical intervention. Examples of the second category include testing for variants recently discovered through research studies to be associated with an increased risk of prostate, colon, breast, and other cancers.
Genetic tests for mutations in genes known to be associated with a high risk for cancer are used to help prevent hereditary cancers for families at an increased risk for developing these cancers. This type of genetic testing is part of the practice of preventive oncology. Results of tests may lead to heightened cancer screening and, in some cases, preventive surgery. Should a mutation not be found in a family with a known genetic syndrome, this may lead to reassurance and relaxation of screening and surveillance.
Genetic variants with a low risk of cancer currently are being studied as part of research studies. It is unclear as to the medical value of such tests ordered directly by consumers, since they do not yet have proven use in medical management, screening, or prevention of cancer. Research regarding these important questions is currently underway.
DTC genetic tests for mutations with a low risk for cancer are generally advertised and sold over the Internet by for-profit companies. Genetic tests for mutations with a high risk for cancer are offered by health care professionals and may be available at academic centers or your doctor's office. These tests may be performed in commercial or academic laboratories.
Q: What are the advantages and disadvantages of these tests?
A: Testing for genetic mutations associated with known syndromes that increase a person's risk of developing cancer is an important part of preventive oncology; however, ASCO recommends, and other professional guidelines agree, that such testing is best offered with genetic counseling. Genetic counseling includes both risk assessment, discussions of options for testing or not testing, as well as a tailoring of cancer screening and prevention strategies for each person. A possible advantage of DTC testing for these proven genetic mutations is increased access to testing for those who can afford it. A possible disadvantage is the absence of in-person cancer genetic counseling by a provider not affiliated with the company providing the test. A perceived advantage of DTC testing is privacy and protection from discrimination. However, a recent Federal law protects people from discrimination, either by insurers or employers, based on genetic information, and in most cases insurers will cover intensified screening or surgical prevention if a mutation is identified. Learn more about preventing discrimination in the workplace.
With regard to DTC testing for variants of low cancer risk, possible advantages include confidentiality and perceived access to cutting-edge research information. Possible disadvantages include the lack of proven information regarding the validity of these tests or what to do with the results. As mentioned, most genetic variants associated with cancer susceptibility are of such low risk that their role in modifying cancer screening or prevention is unproven. Therefore, these tests are generally ordered outside of the context of a doctor-patient relationship. In addition, confidentiality of genetic tests provided by a doctor is protected under a Federal law called the Health Insurance Portability and Accountability Act (HIPAA), while most DTC tests do not have these protections.
In recent guidelines, ASCO reaffirms that all genetic testing be offered in the context of genetic counseling. Ideally, the person providing that counseling would have a responsibility only to the patient or client, and not to the company providing the genetic test.
An additional disadvantage of DTC testing for cancer risk outside of the doctor-patient relationship is that the patient's cancer doctors may not be able to provide guidance about the test results since they are unfamiliar with a test of unproven medical value. Such non-medical tests will also likely not be covered by health insurance.
Q: What type of genetic testing is most useful for patients and their families?
A: Testing for mutations of genes known to be associated with hereditary risk of breast, ovarian, prostate, colon, and other adult and childhood cancers is now an accepted part of medical practice. In such situations, identification of a genetic mutation can lead to tailored screening and follow up, possibly including preventive surgeries for some people. Such testing, provided by a doctor or experienced genetics health professional, can be an important part of the preventive care of families affected by hereditary cancers.
Current research is also identifying many variants that are associated with a risk for common adult cancers. At this point in research, the risks associated with most of these variants are not increased enough to change current cancer screening or prevention strategies. However, ongoing research will likely identify combinations of genetic variations, as well as newer types of variations, which will lead to the ability to better tailor cancer prevention and screening. Therefore, it is ideal, as ASCO recommends, that access to testing for genetic variations of low risk be offered in the context of ongoing research studies. Although not related to familial cancer risk, there are some genetic variants associated with response to treatments for a variety of conditions. These tests should be performed as part of medical treatment for those conditions.
Q: How could the results of a genetic test change a patient's recommended screenings?
A: For tests of genetic mutations of genes associated with known syndromes of cancer susceptibility, a test result could lead, for example, to a risk-reducing surgery of the breast, ovaries, or colon. Genetic test results can also lead to increased screening; examples of increased screening include magnetic resonance imaging (MRI) of the breast, blood tests for markers of prostate cancer, and colonoscopy tests beginning at an early age and performed more frequently, as well as other screening strategies. Recently, specific treatments have been shown to be more effective for patients with certain genetic mutations. Currently, there are no known specific medical interventions for cancer screening or prevention based on results of DTC testing for variants for cancer risk, as provided by a number of for-profit laboratories.
Q: What should patients know about genetic testing? What should they look for if considering a DTC genetic test?
A: Consumers should not confuse genetic testing for mutations associated with high risk of cancer with DTC testing for variants of very low risk for cancer. At present, DTC testing for genetic variants with a very low cancer risk is not part of medical management. In addition, people should be aware that such testing is not currently regulated by most Federal and state guidelines. Therefore, there are often no independent checks on the quality or accuracy of the genetic testing being provided directly to consumers by many for-profit companies. Because these tests are now being offered outside of a patient-doctor relationship, and are of unproven medical use, consumers should be careful not to over-react to results. For example, such DTC testing offers the risk of false reassurance or false alarm. In addition, as pointed out in recent ASCO recommendations, people should ask about the possible future commercial or research use of their DNA testing samples. These uses are generally spelled out in academic centers and should also be known if a person sends a DNA sample to a commercial for-profit laboratory.
When seeking DTC genetic testing, people should learn whether the commercial laboratory meets testing guidelines established by the state in which they live, as well as current Federal regulatory provisions. ASCO and Federal advisors have called for the creation of a mandatory registry of genetic test providers to be available to consumers. Families can always seek second opinions on the need for or interpretation of genetic testing from health professionals not employed by for-profit testing companies. If seeking DTC testing, people should ask about confidentiality issues, such as policies related to privacy and security of the genetic information that is obtained by the for-profit testing company. In its recent statement, ASCO identifies 14 specific elements of informed consent for cancer susceptibility testing, which can also be used as a guide by consumers considering DTC testing. In addition to the issues above, these elements include discussion of alternatives to genetic testing, psychological implications of test results, plans for notification of the family, as well as plans for follow-up after testing.
While there is a rapid pace of scientific discovery in the field of cancer genetics and the growth of for-profit genetic testing companies, ASCO believes that the basic principles established regarding informed consent and assurance of the quality of cancer genetic services remain a priority. Genetic testing and, in the future, variant testing, can provide important new tools to be used to decrease the burden of familial cancer.
Dr. Offit is the Chief of Clinical Genetics Service at Memorial Sloan-Kettering Cancer Center in New York City and a member of the ASCO Ethics Committee.
Last Updated: January 11, 2010