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BRCA-1 and BRCA-2

Also known as: Breast cancer gene 1 and 2

At a Glance

Why Get Tested?

To assess the risk of developing breast or ovarian cancer

When to Get Tested?

If you have a strong family history of breast or ovarian cancer

Sample Required?

A blood sample drawn from a vein in the arm

The Test Sample

What is being tested?

BRCA-1 and BRCA-2 are two genes that are linked with hereditary breast and ovarian cancers. An estimated 10% to 15% of all cases of breast cancers are inherited. About 5% are due to mutations in the BRCA-1 gene and about 5% are due to mutations in the BRCA-2 gene. Only BRCA-2 mutations have been linked to risk of male breast cancer.

How is the sample collected for testing?

The test for BCRA mutations is done on a blood sample collected by needle from a vein in the arm. The test does not require surgical biopsy of breast or ovarian tissue.

The Test

How is it used?

The tests for BRCA-1 and BRCA-2 use the DNA in white blood cells to detect mutations in the BRCA genes. This test can then tell you if you have mutations of the two genes that have been associated with the development of breast or ovarian cancer.

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When is it requested?

Individuals with a strong family history of breast cancer or ovarian cancer may want this test. They may want to use the results to help them decide whether to take steps that may prevent breast or ovarian cancer from developing. However because we don't know how effective the options for prevention are, people who are considering taking this test should seek genetic counselling. In this way they can learn about and understand the implications of the test (see 'Is there anything else I should know?' below).

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What does the test result mean?

Since there are hundreds of possible mutations of BRCA genes, test results must be interpreted by taking into account a person's family history. A genetic counsellor should explain the meaning of the results and offer advice to the individual and to other family members about options for decreasing risk. Counselling advice should be offered both before testing takes place and after receiving test results.

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Is there anything else I should know?

Your test results can affect other family members. When one member of a family is tested for BRCA mutations, issues often arise about how or whether to share this information with other family members. Seek advice from your doctor before asking for this test.

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Common Questions

1.  If the BRCA test is positive, what are my treatment options?

If the BRCA test is positive, the treatment options include increased frequency of check-ups (e.g., mammography, blood tests for CA-125, or transvaginal ultrasonography); medications that could reduce risk (e.g. oral contraceptives or tamoxifen); or surgical removal of the ovaries or breasts.

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2.  If the test is positive, how likely am I to get breast or ovarian cancer?

Your risk will depend on your family history and will need to be determined by a genetic counsellor. Research studies have reported that of every 1000 women positive for BRCA mutations, between 330 and 423 will develop breast cancer by age 50 and between 70 and 90 will develop ovarian cancer by age 50. The risk increases with age.

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3.  If the test is negative, how likely/unlikely am I to get breast or ovarian cancer?  

The same research studies mentioned in question 2 reported that for every 1000 women negative for BRCA mutations, between 12 and 45 will develop breast cancer by age 50 and between 3 and 4 will develop ovarian cancer by age 50. The risk increases with age.

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4.  Where can I get this test?

The test can be requested by your doctor if it is considered appropriate and should be accompanied by genetic counselling. The blood sample will be sent to a laboratory that specialises in genetic testing.

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.