Genetic Cancer Testing
If you have a family history of cancer, depending on the type of cancer, genetic testing can help to assess the likelihood that you will also develop cancer in your lifetime. In addition, a genetic counselor will be able to study your family history and recommend the tests that are useful for you.
How are mutations linked to cancer?
Mutations are common changes that occur in the DNA of all the cells of the human body. Most of the time cells can correct such changes. Sometimes however, a mutation (or a series of consecutive mutations) can cause cancer when it damages a distinct gene. There are specific genetic tests that detect mutations associated with distinct types of cancer (e.g. BRCA1 and BRCA2 in hereditary breast cancer).
What types of genes are linked to cancer?
- Tumor suppressor genes limit cell growth by monitoring how quickly cells divide into new cells. If the gene is mutated, cells can grow uncontrollably into a tumor. (e.g. BRCA1 and BRCA2 – hereditary breast cancer)
- Oncogenes can turn a healthy cell into a cancerous cell. These mutations are acquired and not inherited. (e.g. RET-hereditary thyroid cancer)
- DNA repair genes fix any mistakes that might occur when the DNA makes a copy of itself. If there is an error in this gene, the mistake is not corrected and the gene becomes a mutation. Mutations in DNA repair genes can be acquired and inherited. (e.g. MLH1 and MSH2 – hereditary colon cancer)
- Many cancers are not linked to a specific gene. In this case, multiple, different genes may be at play or might even interact with the environment to cause cancer.
How does genetic testing predict the likelihood of cancer?
In certain situations, genetic testing for cancer risk and the study of the family history help to estimate the likelihood that an individual will develop cancer in his or her lifetime. The genetic test is done in a blood sample that is subsequently studied in the laboratory. The results are interpreted by a genetic counselor in conjunction with the family history and other medical information. Afterwards, the counselor will explain the implications for the family. It is important to understand however, that no test offers 100 percent of diagnostic certainty which means that it may not be able to identify a mutation. In addition, not everyone with a genetic predisposition will develop cancer.
Should I consider genetic testing for cancer?
You should probably should consider genetic testing if you have a positive family history for cancer. We are able to run a genetic test for any gene abnormalities that may cause the cancer. Using this test, you will have a better understanding if you a carry a gene abnormality that explains the cancer running in your family. You will also understand the risk of developing that same type of cancer and foresee the risk of passing the same faulty gene on to your children.
What other factors should I consider?
Testing results may relieve anxiety if there is a family history. Conversely, learning about a predisposition may cause depression, anxiety or guilt. It is important to remember that the test does not change anything. It simply offers additional information that you did not have before the test. Our genetic counselors are trained to support you so that you can use the information in a positive, proactive manner.