At a glance

Also known as

Breast cancer gene 1 and 2

Why get tested?

To assess the risk of developing breast or ovarian cancer associated with inheriting mutations in the BRCA1 or BRCA2 genes

When to get tested?

If you have a strong family history of breast or ovarian cancer, following appropriate pre-test genetic counselling

Sample required?

A blood sample drawn from a vein in the arm

What is being tested?

BRCA1 and BRCA2 are two tumour suppressor genes. Normally, these genes help prevent cancer by producing proteins that repair damage to DNA (the genetic material in a cell). Certain changes (mutations) in these genes disrupt the function of the protein product and are associated with hereditary breast and ovarian cancers.

According to Cancer Australia, about 13,000 women in Australia are diagnosed with breast cancer each year and about 1300 women with ovarian cancer. In most of these women, their cancers are sporadic, but about 5-10% of these women have a familial predisposition to breast/ovarian cancer. Approximately 20% of the familial breast/ovarian cancer (i.e. 1-2% overall) are due to a harmful mutation in the BRCA1 or BRCA2 gene.  Men can also inherit an increased risk of developing breast cancer, occasionally from mutations in BRCA1, but primarily from mutations in the BRCA2 gene.

The BRCA1 and BRCA2 genes are present in every cell of the body.  To detect mutations in the genes, DNA needs to be extracted from cells, and blood is the most easily accessible source of that DNA. 

How is the sample collected for testing?

The test for BRCA 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?

There are hundreds of different BRCA1 and BRCA2 mutations that have been reported. In most patients with a strong family history of breast/ovarian cancer, it is necessary to first test an affected individual in the family to determine whether the predisposition to breast/ovarian cancer in the family is due to a BRCA1/2 mutation, and if so, what the particular mutation in the family is. This is known as diagnostic testing. Once the ‘familial mutation’ is found, other family members can then be tested for that specific mutation to determine their personal cancer risk. This is known as presymptomatic testing, and helps the patient with deciding whether to take steps such as prophylactic surgery that may reduce the likelihood of developing breast or ovarian cancer in the future.

When is it requested?

BRCA testing is usually requested for women with a strong family history of breast cancer or ovarian cancer, or for women with a relative who has a known BRCA1 or BRCA2 mutation, and this is its primary use. It is not recommended as a screening tool for the general population. Someone who is considering testing should talk to her doctor and seek professional genetic counselling by a qualified professional prior to testing.

What does the test result mean?

The degree of risk conferred with a positive result is difficult to quantify for a specific person. Results must be interpreted in conjunction with the tested person's personal and family history. A genetic counsellor or familial cancer specialist should explain the meaning of the results, explain treatment options for the individual that are intended to decrease risk, and testing options for other family members.

A negative result does not mean that a woman will not develop breast or ovarian cancer. It simply indicates that the person tested is not at increased risk for developing hereditary breast cancer or ovarian cancer related to the BRCA mutations for which he/she was tested. It is important to remember that >95% of breast cancers are not associated with a BRCA mutation. Furthermore, in the general population, the lifetime risk of developing breast cancer is approximately 10% and the lifetime risk of developing ovarian cancer is about 1%. The risks increase with age.

The presence of a BRCA1 or BRCA2 mutation means that the person tested is at an increased risk for breast and/or ovarian cancer, but it does not mean that she will definitely develop cancer. Even within a family with the same BRCA mutation, not everyone will develop cancer and those that do may develop it at different times during their life. Estimates of lifetime risk for breast cancer in women with BRCA1 or BRCA2 mutations vary from 40% to 90% and depend on the actual mutation and other genetic and environmental factors (e.g. diet, smoking, etc.). Estimates of risk for ovarian cancer ranges from 15% to 40%.

Is there anything else I should know?

Positive test results may have implications for 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 a genetic counsellor about communication of results with other family members.

Pre- and post-test consultation with a health care provider knowledgeable about genetic testing cannot be overemphasized. There are many issues to be considered when preparing for a genetic test and upon learning the results, and a genetic counsellor has the knowledge and expertise to help sort through them.

Common Questions

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

If the BRCA test is positive, the options include increased frequency of check-ups (e.g., mammography); medications that could reduce risk (e.g. tamoxifen); or surgical removal of the ovaries or breasts.

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

See the previous section "What does the test result mean?"

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

A negative result does not completely exclude the possibility of developing breast or ovarian cancer. See the previous section ‘What does the test result mean?’ for more information. 

Where can I get this test?

The test can be requested by specialists in familial cancer clinics or clinical geneticists if it is considered appropriate and should be accompanied by pre- and post-test genetic counselling. These services are available across Australia, and can be accessed by referral from your general practitioner. The blood sample will be sent to a laboratory that specialises in genetic testing.


Last Review Date: June 10, 2012