Before Undergoing Genetic Testing
Testing for mutations in genes that give an increased risk for
cancer is complicated. The concepts are important to understand when
considering cancer susceptibility gene testing.
You may wish to speak with your doctor 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 (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%.
- 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 will not 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 in the
gene the mutation is located.
- Other genes and environmental
risks 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/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/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 which provides protection against genetic discrimination
in health insurance, life insurance, and employability at the state
level can be found at the National Human Genome Research Institute website.
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.