Breast Cancer (BRCA) Gene Test
A breast cancer (BRCA) gene test is a blood test to check for changes (mutations) in genes called BRCA1 and BRCA2. This test can help you know your chance of getting breast cancer and ovarian cancer. A BRCA gene test does not test for cancer itself.
A woman's risk of breast and ovarian cancer is higher if she has BRCA1 or BRCA2 gene changes. Men with these gene changes have a higher risk of breast cancer. And both men and women with these changes may be at higher risk for other cancers. You can inherit the gene changes from either your mother's or father's side of the family.
This test is only done for people who have a strong family history of breast cancer or ovarian cancer or who already have one of these diseases. If none of these is true for you, you are not likely to have a BRCA gene change. Only about 2 or 3 out of 1,000 adult women have a BRCA gene change. That means 997 or 998 out of 1,000 women do not have this change.footnote 1
There are some important things to keep in mind when you are thinking about having a BRCA gene test.
- A negative BRCA result does not guarantee that you will not get breast cancer. BRCA gene changes do increase the risk of breast cancer. But there are other gene changes that may cause cancer, too.
- If a family member has breast or ovarian cancer, think about asking that person to have the BRCA test before you decide to have the test. If your family member's results are negative, it probably will not help to test the rest of the family.
- Most health plans will cover the cost of genetic testing if you meet the conditions for testing.
- You may worry that your genetic information could affect your job options or ability to get private insurance. For information about non-discrimination regulations in Canada or in your province, contact your provincial ministry of health.
- Experts don't recommend BRCA testing for women who do not have family risk factors for BRCA changes. If your family doesn't have risk factors, the BRCA test is not likely to give you any useful information about your risk of breast cancer. Women from average-risk families rarely have a positive test. And sometimes the test shows a gene change when there when there isn't one. This is called a false-positive result.
It is very important to have genetic counselling both before and after this test. It can help you understand the benefits, risks, and possible outcomes of the test.
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Why It Is Done
A BRCA gene test is done to find out if you have BRCA gene changes that increase your risk of breast and ovarian cancer.
You may be more likely to have a BRCA gene change if you:footnote 1
- Were diagnosed with breast cancer before age 50.
- Have had breast cancer in both breasts.
- Have had breast cancer and ovarian cancer.
- Have one or more male family members who have had breast cancer.
- Have multiple cases of breast cancer in your family.
- Have at least one family member who has had BRCA-related cancer.
- Are an Ashkenazi Jew (a Jewish person whose ancestors came from Eastern Europe).
The results of a BRCA gene test can help you find out how high your cancer risk is. If it is high, you might decide to take steps to lower your risk. There are several things you might do, such as:
- Have checkups and tests more often.
- Have surgery to remove your breasts.
- Have surgery to remove your ovaries.
- Take medicines that may help prevent breast cancer.
If you have a family member who has breast or ovarian cancer, you may want to ask that family member to have a gene test first. If your relative's test finds a changed BRCA gene, you and other family members can then be tested for that specific gene change. But if your family member's test is negative, it is not likely that you carry the gene change.
How To Prepare
The information from a BRCA gene test can have a deep impact on your life. So it is very important to get genetic counselling before you have this test. A genetic counsellor can talk with you about the test, what the results mean, and your medical and emotional concerns.
You will be asked to sign a consent form that says you understand the risks of the test and agree to have it done.
Talk to your doctor if you have any concerns about the need for the test, its risks, or how it will be done. To help you understand the importance of this test, fill out the medical test information form (What is a PDF document?).
How It Is Done
The health professional taking a sample of your blood will:
- Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
- Clean the needle site with alcohol.
- Put the needle into the vein. More than one needle stick may be needed.
- Attach a tube to the needle to fill it with blood.
- Remove the band from your arm when enough blood is collected.
- Put a gauze pad or cotton ball over the needle site as the needle is removed.
- Put pressure on the site and then put on a bandage.
How It Feels
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
It is common to worry before a BRCA test and while waiting for its results.
There is very little chance of a problem from having a blood sample taken from a vein.
- You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
- In rare cases, the vein may become swollen after the blood sample is taken. You can use a warm compress several times a day to treat this.
The information from a BRCA test can affect you and your family in many ways. For example:
- You may feel anxious or depressed if you learn that you have a high risk of cancer and could pass that risk onto your children. This information could also affect your relationship with your partner or other family members.
- If you test positive for a BRCA gene change, you will face hard decisions about options to reduce your risk, such as surgery to remove your breasts (mastectomy).
- You may worry that your genetic information could affect your job options or ability to get private insurance. For information on the risks of genetic discrimination in Canada, talk with your doctor or contact the Canadian Coalition for Genetic Fairness at 1-800-998-7398. Or visit its website at www.ccgf-cceg.ca.
It may take several weeks to get the results.
No changes were found in the BRCA1 or BRCA2 genes.
A negative result and your overall family risk must be considered together. If you have a strong family history of breast or ovarian cancer, your cancer risk may be higher than normal even if you have a negative BRCA result.
- Only about 5% to 10% of breast and ovarian cancers are linked to the BRCA1 or BRCA2 gene change.
- It is possible that you may have other gene changes that make cancer more likely.
BRCA1 or BRCA2 gene changes are present.
Women who have BRCA1 or BRCA2 gene changes have:
- Women with a mutated BRCA1 or BRCA2 gene have a 40% to 85% chance of developing breast cancer in their lifetime.
- Women with a mutated BRCA1 gene have a 25% to 65% chance of developing ovarian cancer in their lifetime.
- Women with a mutated BRCA2 gene have a 15% to 20% chance of developing ovarian cancer in their lifetime.
Your range of risk will depend on the type of genes you have and your personal and family history of cancer.
Men with BRCA2 mutations, and to a lesser extent BRCA1 mutations, are also at increased risk of breast cancer. Men with harmful BRCA1 or BRCA2 mutations have a higher risk of prostate cancer.
Uncertain (variant of uncertain significance, or VUS)
This result may mean that a gene change is present, but it is hard for your doctor to tell if the change is important and if it affects your chances of getting cancer.
What Affects the Test
Your doctor will talk with you about anything that may keep you from having the test or that may change the test results.
What To Think About
Genetic counselling before and after a BRCA test can help you understand the benefits, risks, and possible outcomes of testing.
- To find doctors who do gene tests and counselling, contact your local chapter of the Canadian Cancer Society at www.cancer.ca.
- To find a genetic counsellor near you, contact the contact the Canadian Association of Genetic Counsellors (CAGC) at www.cagc-accg.ca.
Other Places To Get Help
- U.S. Preventive Services Task Force (2013). Risk assessment, genetic counseling, and genetic testing for BRCA-related cancer in women: U.S. Preventive Task Force recommendation statement. U.S. Preventive Services Task Force. http://www.uspreventiveservicestaskforce.org/uspstf12/brcatest/brcatestfinalrs.htm. Accessed March 6, 2014.
- National Comprehensive Cancer Network (2015). Genetic/familial high-risk assessment: Breast and ovarian. NCCN Clinical Practice Guidelines in Oncology, version 1.2015. http://www.nccn.org/professionals/physician_gls/pdf/genetics_screening.pdf. Accessed June 2, 2015.
Adaptation Date: 12/3/2017
Adapted By: HealthLink BC
Adaptation Reviewed By: HealthLink BC
Adaptation Date: 12/3/2017
Adapted By: HealthLink BC
Adaptation Reviewed By: HealthLink BC
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