Breast and Ovarian Cancer (BRCA) Genetic Test

What is a breast and ovarian cancer genetic test?

The blood test for breast or ovarian cancer looks for changes, or mutations, in the BRCA1 and BRCA2 genes. Normally, these genes help control cell growth. Cancer occurs when cells change and grow out of control. Women who inherit these BRCA gene changes have a higher-than-average chance of getting breast or ovarian cancer.

Breast cancer

• Most women who have breast cancer do not have a family history of the disease.
• A family history of breast cancer is not the same as having a BRCA gene change. Most women who have a family history of breast cancer do not have BRCA changes in their family. Between 5% and 10% of women who have breast cancer have an inherited form of the disease. Many of these are related to BRCA1 and BRCA2 gene changes.¹
• Inheriting a BRCA gene change does not mean you will get cancer.
• Not having a BRCA gene change does not mean you will not get breast cancer—it means you have an average chance of getting cancer.
• Women who have a BRCA1 or BRCA2 gene change have a 3 to 7 times higher chance of getting breast cancer compared with other women who do not have these gene changes.¹
• Breast cancer is very rare in men but BRCA2 gene changes have been linked to male breast cancer.

Ovarian cancer

• A woman with a BRCA gene change could have a 16% to 60% chance of ovarian cancer. This means that as many as 600 out of 1,000 women with this change may get ovarian cancer. A woman without BRCA changes has a 17 in 1,000 chance of ovarian cancer.¹
• Inheriting a BRCA gene change does not mean you will get ovarian cancer.
• Not having a BRCA gene change does not mean you will never get ovarian cancer—it means you have an average chance of getting it.

If you have a strong family history of breast or ovarian cancer, this test can be one factor you consider when deciding whether you should take steps to lower your chance of cancer. Those actions may include taking medicine or having your breasts, ovaries, or both, removed. In deciding whether to have the test, you need to weigh your personal and family risks and your feelings, finances, and relationships with others.

Consider having genetic counselling to help you understand the benefits, risks, and possible outcomes of testing. Genetic counsellors are trained to explain the test and its results. To find health professionals who provide genetic testing and counselling, contact your local chapter of the Canadian Cancer Society or the National Cancer Institute of Canada at (416) 961-7223 or http://www.ncic.cancer.ca. To find a genetic counsellor near you, contact the Canadian Association of Genetic Counsellors (CAGC) at http://www.cagc-accg.ca.

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Author:	Alison Allen Shannon Erstad, MBA/MPH	Last Updated: October 31, 2007
Medical Review:	Anne C. Poinier, MD - Internal Medicine Douglas A. Stewart, MD - Medical Oncology
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