Genetic Testing for Cancer
What Is a Gene and How Does It Affect the Growth of Cancer?
There are 23 pairs of chromosomes in the body, half inherited from the mother, half from the father. These chromosomes contain DNA (deoxyribonucleic acid). Genes are the part of DNA that control the functioning of the body’s cells. It is estimated that there are 20,000 to 30,000 different genes within each cell.
Genes control how the body functions by making proteins. Each protein has a different function and is a messenger for the cell, “telling” it:
- Its rate of growth
- How often to divide
- Its lifespan
Every gene receives “instructions” on how to make its protein, so the protein functions correctly within the cell.
When genes change, or mutate, they either create an abnormal protein or inhibit the protein from forming at all. If a protein is abnormal, the instructions it gives to the cell are incorrect. This is what can cause cells to multiply at a very rapid rate and become cancerous.
The Two Types of Cancer
Each type of tissue in the body has a particular type of cell. For example, the cells that compose breast tissue are different than those that compose lung tissue, and both are different than the cells that compose colon tissue.
All cancers are genetic mutations, as the information or misinformation for the cell begins with the genes. These mutations cause the cells to divide many times and form a tumor, or abnormal mass. However, the source of the mutations may differ:
- Acquired mutations are the result of damage to genes in a specific cell during a person’s lifetime. The cancer that results from this is called “sporadic cancer,” because they are not found in every cell of the body. The damage may come from ultraviolet radiation, tobacco, environmental factors, viruses, or even age.
- Hereditary, or “germline” mutations, occur in a sperm cell or egg cell. These are passed directly from parent to child, at the time of conception. Unlike acquired mutations, these are copied into every cell in the body, including reproductive cells. This is how it passes from generation to generation. This type of cancer accounts for only 5 percent to 10 percent of all cancers.
The Likelihood that a Mutation Will Become Cancerous
The good news is that mutations happen often, but a single mutation is not likely to cause cancer. Further, a mutation is not necessarily harmful; it may be neutral or in some cases, even beneficial. Also, germline mutations do not necessarily result in cancer in every person who has them.
Genetic Testing and Why It Is Important
A genetic test examines a sample of a person’s cells to see if there are abnormal genes, proteins or chromosomes. For chromosomes, the test analyzes the number, arrangement, and characteristics. The type of test that are run typically depend on the suspected disorder.
Genetic testing can be performed on a sample of blood, hair, skin, or other types of tissue. You have no doubt seen a forensics team on TV swab the inside of someone’s cheek to gather saliva or ask for a hairbrush or toothbrush from which a sample can be collected.
Genetic testing can be valuable, whether the results are positive or negative for gene mutations. Either way, they can relieve the burden of uncertainty. If they are negative, they can reduce or eliminate the need for unnecessary checkups and screenings. If they are positive, they can help you and your medical team determine appropriate steps for possible prevention, ongoing monitoring and treatment, if warranted.
Genetic Testing for a Newborn or Fetus
Newborn screening, which is always performed on a very small sample of blood, taken from the infant’s heel, are invaluable in managing expectations, as well as planning around the growth and development of the child. This is particularly true when hereditary cancer is a possibility or suspected.
Along with the types of samples previously mentioned, genetic testing can be performed on a sample of amniotic fluid, which is the fluid that surrounds the fetus in the womb. The results of such a combination of tests can be extremely useful in helping a couple make decisions about having children.
Symptoms of Hereditary Mutations
When several family members contract the disease, people’s first thought is that the cancer may be hereditary. However, when it comes to hereditary mutations, appearances are not always a reliable indicator. Unless, of course, known genetic risk factors have already been identified, the mutations may be caused by environmental factors, such as smoking in the home or a polluted water supply, as was the subject of a popular film, “Erin Brockovich.”
If there is a personal and family history of any of the following, cancer may run your family:
- Cancer at a young age
- Particularly rare cancers at any age
- Multiple relatives on the same side of the family, who have been diagnosed with the same or related cancers over a number of generations
Also, while not rare, certain types of cancers, such as breast or ovarian cancer, may also tend to run in families.
Interpreting the Results of Genetic Testing
Interpreting the results is not done in a vacuum. Results are considered in relation to a person’s own medical history, family history and the type of tests that were done.
Pre-symptomatic positive results cannot predict exactly how much risk there is for developing a disorder. Nor can they conclusively predict the course of a disorder or its severity.
As a result of a medical or family history, your healthcare team may decide that further testing is warranted, even when the results are negative.
Why Choose the Beverly Hills Cancer Center for Genetic Testing
The Beverly Hills Cancer Center is recognized as one of the most advanced cancer centers in the world and ranked the #1 Radiology and Imaging Center by Expertise in Los Angeles. Our leading-edge technology, breakthrough research and variety of targeted treatment options combine to deliver the most advanced cancer testing and treatment in an atmosphere of compassionate support.
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