Before undergoing genetic testing
Testing for mutations in genes that give an increased risk for cancer is complicated. Below is a description of concepts that are important to understand when considering cancer susceptibility gene testing. You may wish to speak with your physician or health care provider, or obtain a referral to a genetic counselor, to find out about specific testing availability applicable to your situation.
- Inquire about laboratory testing methods.
Testing methods vary from laboratory to laboratory and may affect the sensitivity of testing (i.e., the likelihood that the lab will identify a mutation in the gene if there is a mutation present). Different laboratory studies have the ability to detect different types of mutations. Accuracy will therefore vary depending upon the type of genetic testing method performed. Sometimes the type of tissue studied also affects the likelihood of finding a mutation (i.e., tumor versus blood sample). Also, some families may have a mutation in a gene, but the mutation is not detectable with the current technology. In these cases, genetic testing may give a false-negative result — one that indicates a normal result when there actually is a problem.
- Not all persons with what appears to be an inherited cancer will have a mutation.
Reasons for this include:
- The accuracy of testing is not 100 percent.
- Testing is not available for all genes associated with a hereditary cancer.
- A mutation is present in the family, however, there is not yet testing available to identify it.
- The individual tested in a family has developed cancer through a nongenetic mechanism (i.e., a sporadic case), while the other cases in the family are due to a germline mutation.
- The family does not have inherited cancer in spite of a clinical presentation that suggests a genetic basis. Some such families may be the result of incorrect reporting of cancer diagnoses in the family.
- If genetic testing is done and no mutation can be identified in an affected family member or members (i.e., one with cancer), testing unaffected relatives for the same gene is not likely to help in clarifying cancer risks.
In this situation relatives of the affected person would remain at increased risk to develop cancer by virtue of their family history.
- Consider the implications of testing results.
- If a person is mutation positive:
- The likelihood of developing various cancers depends upon the gene in which the mutation is found and in some cases, where the mutation is located in the gene.
- Other genes and environmental risk factors may modify cancer risk.
- Test results give a probability, not certainty, of cancer development and do not indicate when cancer may develop or the stage/grade of a potential tumor.
- Test results may help a person to be proactive about cancer surveillance or preventative measures.
- Test results may not change recommendations for medical management or cancer surveillance.
- If a person is mutation negative:
- If there is a known mutation in the family, then he or she is not at increased risk of developing cancer based on the family history but is at general population risk. If the individual tested belongs to a particular ethnic group where common mutations have been identified, then relatives should consider testing for all ethnic-specific mutations, not just the one present in the family.
- If there is not a known mutation, a negative test result is uninformative. The family may have a mutation in the gene tested that is not detectable with the current technology or a mutation in a different gene, since many cancer syndromes are genetically heterogeneous (caused by mutations on one of several different genes).
- If a variant of uncertain significance is found:
In this case, an alteration in the DNA of a gene has been identified, but it is unknown whether the alteration will actually affect the function of the gene and, as such, influence cancer risk. Further studies may be indicated (if available). If a significant family history is present, such a result does not rule out a hereditary cancer syndrome in a family.
- Consider the psychosocial implications of testing.
Increased or decreased emotional distress may be experienced after testing for mutations in cancer susceptibility genes. Relationships with family members may change, particularly if one person is mutation positive, while another is mutation negative. Some individuals experience guilt when they are the only person in their family without a mutation. Communication between family members can improve or stop altogether depending upon test results. It is important to try to anticipate potential problems in the family related to testing before proceeding.
- Consider the economic impact.
Testing for cancer susceptibility genes may or may not be covered by insurance, and can be costly. Check with your insurance company about coverage prior to having testing performed. Some laboratories perform testing for free or for a nominal fee, if part of a research study. Additionally, programs are sometimes available to assist with covering the cost of genetic testing, depending upon the laboratory.
- Consider the risks of genetic discrimination.
Many people are concerned about the risk for genetic discrimination. Genetic discrimination is when a person is discriminated against based on their genetic information alone. An example of genetic discrimination would be if an insurer were to increase your premiums because they found out you carry a mutation that increases your risk to develop cancer, even though you do not currently have cancer and may not develop the disease. In this situation, information about legislation at the state level that provides protection against genetic discrimination in health insurance, life insurance and employability can be found at the National Human Genome Research Institute. On the federal level, the Health Insurance Portability and Accountability Act of 1996 provides some protection against genetic discrimination with regard to health insurance for individuals with group policies.
- Remember that testing options change.
Remember that technology is rapidly advancing. If you are a person for whom no testing currently exists, testing options may become available in the near future.
- Take your time.
Do your homework and be sure to take the time to explore the above issues before undergoing testing for mutations in cancer susceptibility genes, in order to fully understand the implications of your test results. Remember, genetic testing is a personal choice, and is not for everyone. Only you can decide what is right for you.