Genetic Testing FAQs



What is genetic testing?

Genetic testing is the process of using medical tests to look for changes (mutations) in a person’s genes or chromosomes. Hundreds of different genetic tests are used today, and more are being developed. Genetic tests are most useful when conducted under the supervision of a genetic counselor who specializes in understanding genetic risks and concepts and is able to provide in-depth genetic counseling about heritable disorders.  Since there are so many genetic tests available, genetic counseling helps to determine which test may be useful to you and your family as well as the implications of different test results.

What are the benefits of genetic testing?

The obvious benefit of genetic counseling and testing is the chance for a better understanding of your risk for an inherited disease. If there is a mutation that increases the risk of cancer identified in a family, a negative result from genetic testing may help or relieve anxiety or uncertainty. In the same way, a positive result can help you make important decisions about your future, perhaps including things you can do to help lower your risk of developing cancer.

If you have already been diagnosed with cancer, genetic testing can help your doctors figure out if there are any other cancers that you may be at risk for, so that screening can be increased.  Sometimes, carrying a genetic mutation may qualify a person for certain treatment options, such as PARP drugs for metastatic ovarian cancer patients that carry a BRCA1/2 mutation.

What are the limitations of genetic testing?

Genetic tests do not give precise answers about whether or not cancer will occur.  A positive test result does not always mean you will get the disease. The test can tell you what might happen, but it cannot tell what will happen. On the other hand, a negative result does not mean you have no risk of getting the disease.  For some genes on the panel, we have national guidelines for management, but for other genes, less information is known about cancer risks and what we should recommend for individuals that have a mutation.

Genetic test results can be complicated.  Possible test results include a positive, negative, or a variant of uncertain significance.  Genetic counseling is important to address the possibility of an inconclusive test result.  Over time, as we learn more about genetics, these variants will get reclassified as disease-causing (pathogenic) or as normal differences between people (benign).

Sometimes genetic testing may be done even though the result has little chance of helping the person. When this happens, the test may create anxiety when the original intent was to relieve it. This is why meeting with a genetic counselor for genetic counseling prior to the test is so important – you’ll want to know exactly how the result could help you and your family. People have a lot of different feelings throughout the testing process, which can include anxiety, guilt or even anger.  Genetic counseling is helpful in addressing the psychological and emotional impact.

Do men need to be tested?

At-risk men should definitely consider genetic testing. Men with mutations in BRCA1/2 are at high risk for prostate cancer (not to mention pancreatic and male breast cancer). These cancers tend to be early onset, more aggressive and more deadly than prostate cancers in the general population. Mutations in other genes may put men at risk for colon, pancreatic, kidney and numerous other cancers. For many of these cancers, there are screening or preventative measures which can be taken to improve overall outcomes and save lives. Additionally, testing a man gives us important information about the risk to his children and potentially other member of the family.

If my test is negative, does that mean I won’t get cancer?

Everyone has a risk of cancer. There is no test, genetic or otherwise, that can tell a person whether or not they will get cancer. Additionally, there is no test that can tell a person that they do not have a hereditary cancer predisposition. There are hereditary cancer genes which have yet to be discovered and are not available for testing. Also, even the best genetic tests do not analyze every area of a particular gene. Therefore, genetic testing is imperfect and a negative test result does not mean that a person’s risk of cancer is necessarily less than we understood it to be before the testing. If a person had a family history of cancer worthy of genetic evaluation, then in absence of a genetic mutation, that patient remains at increased risk of the cancers seen in the family. It is important to remember that familial cancer (i.e. a clustering of breast cancers in a family with no detectable mutation) increases risk for the entire family and these individuals may benefit from increased surveillance even though genetic testing is not useful for these families.

Do I have the BRCA gene?

Patients often are confused about genetics and may have been led to believe that people with hereditary cancer predispositions (like Angelina Jolie) have a gene which the rest of us do not. This is not the case. We all have 2 copies of each of the genes tested on any given hereditary cancer panel. Therefore, it is not whether a person has the BRCA gene, but rather whether that gene has the correct sequence or is mutated and not functioning.

If I already had negative BRCA1/2 testing, do I need more testing?

Maybe. BRCA1/2 testing has evolved and improved over time. The first several years of testing included only sequencing of the gene and did not pick up large deletions, duplications, and rearrangements. People who had this inferior testing qualify for updated testing of the BRCA1/2 genes. More importantly, from the late 1990s until a few years ago, we were only able to test for BRCA1/2 (as far as breast cancer genes are concerned). We now know that BRCA1/2 account for only 25-50% of hereditary breast cancer. We can test for more than 20 genes associated with breast cancer now. People who have tested negative for BRCA1/2 may find that they carry a mutation in one of these other hereditary cancer genes.