Genomic & Genetic Testing
Cancers are caused by genetic mutations, which are changes in DNA – the information plan for the growth and control of cells. Several genes have been identified that are known to be associated with the development of prostate cancer. These gene mutations may be inherited or developed during a person’s lifetime. Your doctor may use specialized gene testing to detect such DNA changes.It is important to understand the differences between the two often-confused terms: genomics and genetics. Genomics is the study of genes and their functions, and genetic testing refers to the study of inherited genes.
Testing for genetic alterations in the tumor may be conducted for several reasons:
- Classifying your cancer into a prognosis or risk group
- Determining the cancer’s ability to metastasize or spread
- Identifying targets for treatment with drugs, and genetic testing refers to the study of inherited genes.
This type of testing is conducted to determine the mutations present or the level of expression of certain genes in your cancer cells. It is usually performed on tumor tissue and may sometimes be applied to cancer cells detected in the blood. The identified mutations or expression patterns may indicate the cancer’s behavior, how aggressive it might be and whether it will metastasize (spread). This information can lead to better decisions about the need for and choices of treatment.Genomic tests are performed on a sample of cancerous tissue taken from a biopsy or surgical specimen. Once a cancer is diagnosed, a genomic test such as Prolaris, Oncotype DX or Decipher may help determine how aggressive the cancer is. In addition to genomic profiling of the cancer, your doctor may recommend testing the cancer for specific genetic mutations such as microsatellite instability high (MSI-H) and deficient mismatch repair (dMMR) genes. This information may help you and your doctor make decisions regarding which therapy is best for your cancer.
Keep in mind, if testing does not identify a mutation that has a specialized treatment, standard of care and clinical trials may be options to consider.
Genetics is the study of genes and the passing of genetic information and traits from parents to children (heredity). Some cases of prostate cancer are inherited, and these abnormalities can be detected in normal cells (blood or cheek swab specimen). Finding mutations in some genes may indicate an increased risk of developing cancer. Tests for these mutations may be performed before or after someone is diagnosed with cancer.A strong family history of cancer or the presence of prostate, breast or ovarian cancers among your relatives are reasons to ask your physician about genetic testing. Knowing whether you have an inherited mutation that may influence your risk of getting cancer is important for your care and follow up, and for your relatives to know.
The following features may indicate a risk of hereditary prostate cancer:
- Mutations in genes MLHL, MSH2, MSH6, PMS2 and EPCAM that cause Lynch Syndrome (Familial Nonpolyposis Colon Cancer)
- Hereditary Breast and Ovarian Cancer (HBOC) Syndrome associated with inherited mutations in BRCA1 and BRCA2 genes
- Family history of breast, colon, ovarian, pancreatic or prostate cancer
- A diagnosis of high-risk, very high-risk, regional or metastatic prostate cancer
- Prostate cancer in three generations on the same side of the family
- Multiple cancers in one relative
- Two or more close relatives diagnosed with prostate cancer before age 55
Sharing Your Family Health History
Choosing to have genetic testing is a decision that affects your entire family. Knowing and sharing the information could help them be screened and monitored closely if they have a gene mutation associated with cancer. Preventing or detecting a cancer early offers the best chance of a successful treatment outcome.A genetic counselor can be crucial to help you understand what the results mean for you and your family and their future health. Once you understand your results, you can choose to share them with your children, siblings, nieces, nephews, etc. Family members may be offered testing if a mutation is found. If a genetic counselor is not on staff at your cancer center, ask your doctor for a referral.
A variety of mutations in a normal gene can increase a person’s risk of developing cancer. Some mutations that can occur in genes include the following.Gene amplification — An increase in the number of copies of a gene, which is common in cancer cells. Some amplified genes may cause cancer cells to grow or become resistant to anticancer drugs.
Gene deletion — The loss of all or part of a gene.
Fusion gene — A gene made by joining parts of two different genes. Fusion genes, and the fusion proteins that come from them, may be made in the body when part of the DNA from one chromosome moves to another chromosome. Fusion proteins produced by this change may lead to the development of some types of cancer.
Overexpression — Too many copies of a protein or other substance, which may play a role in cancer development.
Rearrangement — A mutation that occurs in chromosomes where portions of the chromosome are not in order, which creates a new gene (not shown).