BRCA

What is being analysed?
BRCA-1 and BRCA-2 are two genes associated with breast and ovarian cancer. About 10-15% of breast cancers are inherited. Of these, about 5% are linked to mutations in the BRCA-1 gene and about 5% to mutations in BRCA-2. Breast cancer in men is associated only with mutations in the BRCA-2 gene.

People with BRCA1 or BRCA2 mutations have a significantly higher risk of developing breast cancer (up to 80%), ovarian cancer (up to 40%), cancer in both breasts and other types of cancer. BRCA mutations are inherited without skipping generations.

How is the sample collected for testing?
Testing for BRCA mutations requires a blood sample taken from a vein. It is the DNA of the white blood cells in the circulation that is used to look for mutations in the BRCA genes. No biopsy of breast or ovarian tissue is therefore needed.

How is it used?
When is it requested?
What does the test result mean?
Is there anything else I should know?

How is it used?
BRCA-1 and BRCA-2 testing can identify mutations in either of these genes that are associated with the risk of breast and ovarian cancer. BRCA testing should be considered for people with a strong family history (close relatives, men or women) of breast and/or ovarian cancer, particularly if the cancer was diagnosed at a young age (<50 years).
 
In specific populations, such as people of Ashkenazi Jewish descent, testing should focus on the specific mutations found in that population. If a specific BRCA-1 or BRCA-2 mutation has been identified in a family member with breast and/or ovarian cancer, the other family members should be tested for that same mutation.
 
When is it requested?
This test is requested for people with a close family history of breast or ovarian cancer. The results can be used to decide on measures to prevent breast or ovarian cancer. Since the effectiveness of these preventive choices is not known, people considering this test should be referred for genetic counselling.
 
What does the test result mean?
Since hundreds of mutations of the BRCA genes are possible, the results should be interpreted taking into account each patient’s family history. An experienced genetic counsellor should explain what the results mean and outline the possible options for reducing risk in the person and in other family members. Genetic counselling should be offered both before and after the test.
A negative result does not rule out the possibility of developing breast cancer, but it rules out the risk of developing inherited breast cancer linked to the BRCA mutations tested.
 
A BRCA mutation indicates a higher risk of developing breast and/or ovarian cancer. However, even if members of a family carry the same BRCA mutation, not all of them will develop cancer, and those who do may develop it at different ages. In people with BRCA-1 or BRCA-2 mutations, the lifetime risk of developing breast cancer and ovarian cancer is 36-85% and 16-60% respectively.

Is there anything else I should know?
Your doctor should explain what a BRCA mutation means before the test, both because the results may also have implications for other family members and because questions often arise about whether and how to share the information obtained.

1. If the BRCA test is positive, what is the risk of breast or ovarian cancer? What can be done?
2. If the BRCA test is negative, what is the risk of breast or ovarian cancer?
3. Where is this test done?
 
 
1. If the BRCA test is positive, what is the risk of breast or ovarian cancer?
The risk of breast or ovarian cancer depends on the family history and is assessed by a geneticist. The literature shows that of 1,000 women with BRCA mutations, between 330 and 423 will develop breast cancer, and between 70 and 90 will develop ovarian cancer, by the age of 50.

–What can be done?
Check-ups can be made more frequent (e.g. mammography, blood tests for CA 15-3 and CA-125, and transvaginal ultrasound); treatments that may reduce the risk can be used (e.g. oral contraceptives or tamoxifen); or the ovaries or breasts can be surgically removed.

2. If the BRCA test is negative, what is the risk of breast or ovarian cancer?
The risk increases with age. The literature shows that of every 1,000 women without BRCA mutations, between 12 and 45 will develop breast cancer and between 3 and 4 will develop ovarian cancer by the age of 50.
 
3. Where can I have this test?
The test can be requested by your doctor if they consider it appropriate, and assessed by a geneticist. The blood sample will be sent to a specialist laboratory for BRCA testing.