Types of Genetic Tests
There are three common tests to search for gene mutations that may cause breast cancer. Your genetic counselor can explain which test is best for you. Which test you have will depend on your personal and family history of cancer, and whether a gene mutation has been identified in your family in the past.
No matter what type of test your genetic counselor recommends, you will have to give the lab a sample of your cells. Labs can take samples from your blood, your saliva (spit), or from cells on the inside of your cheek.
Giving a blood sample is the same as having blood taken for many other tests you may have needed in the past. A nurse or other trained professional will use a needle to draw blood from a vein in your arm, usually one on the inside of the elbow.
If you have to send a saliva sample, you will simply spit into a cup. You may not be able to eat, drink, smoke, chew gum or brush your teeth for 30 minutes before. You may also have to rinse with mouthwash. This is to make sure the saliva is as pure as possible for the test.
If you have a cheek-swab test, a nurse or other professional will gently roll the end of a cotton swab along the inside of your cheek to collect cells.
It may take 2-3 weeks, or more, for your test results to come back. If you need results faster to make treatment decisions, you may be able to rush the test results.
If someone in your family has already tested positive for a breast cancer-related gene mutation, a single-site test can look for that same mutation in your DNA. Single-site tests may also be used if you come from an ethnic group more likely to have certain gene mutations, such as the BRCA1 and BRCA2 mutations found in the Ashkenazi Jewish population.
Your genetic counselor may recommend this test if no specific mutations have been found in other members of your family, and depending on your personal and family history of cancer.
Gene panel tests look for many different mutations in many genes, all at once. Researchers are studying genetic causes of cancer at a rapid pace, and new genes related to higher cancer risk are being discovered.
A gene panel test can look at your DNA for many of these mutations. But remember that not all mutations have the same impact on whether you develop cancer.
There are three types of mutations a gene panel can look for:
- High-risk gene mutations. In addition to mutations in BRCA1 and BRCA2, there are a few other mutations in other genes that we now know are linked to a higher risk of breast or ovarian cancer. Research keeps adding more genes to this list.
- Moderate-risk gene mutations. These are mutations in genes linked to a somewhat higher risk for certain cancers, but not an extremely high risk. Additional research could show that mutations in these genes cause a higher risk than previously thought, but the evidence is not there now.
- Genes suspected to be related to breast cancer. Some mutations are thought to cause higher risk of breast cancer, but we don’t have enough data to know. Ongoing research could lead to more information about these genes at any time. But right now we don’t know enough to make specific recommendations if a mutation is found in these genes.
When your genetic counselor recommends gene panel testing, he or she will discuss with you which types of genes and mutations may be most helpful for the test to focus on. In many cases, it makes sense to look just at high-risk genes. In some cases, it might make sense to look at moderate-risk and suspected-risk genes, too.
Cost may also be a factor. The more genes tested in a panel, the more the test may cost. The cost of these genetic tests can be anywhere from several hundred to several thousand dollars. In some cases, your insurance may cover both the genetic counseling and the test. Call your insurance company or check your healthcare plan’s explanation of benefits to find out what they cover before you get tested.
Several labs offer genetic tests for breast cancer. Which lab your sample is sent to may be decided by your doctor, your insurance company, or you may have a choice. The labs below offer some popular tests. We list them in alphabetical order: