Breast and Ovarian Cancer (BRCA) Genetic Test

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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 www.ncic.cancer.ca. To find a genetic counsellor near you, contact the Canadian Association of Genetic Counsellors (CAGC) at www.cagc-accg.ca.

What do the results mean?

A negative result means you do not have changes in BRCA1 and BRCA2 genes. A positive result means you do have a change on one or both of the genes. Sometimes the test result is uncertain—neither positive nor negative.

It may take several weeks for you to get the results.

Is testing accurate?

No test is 100% accurate. The BRCA test cannot find all possible changes to the genes. It is possible that the test will show you do not have genetic changes when you do. This is called a false-negative test result.

Your test would be most helpful if you first had a close family member who had breast or ovarian cancer genetic tests. If this person tested positive, it means there is a known BRCA change in your family. If the family member's test results are negative, it usually is not helpful to test the rest of the family.

If you have a strong family history of breast or ovarian cancer, a negative BRCA result does not mean that you will not get cancer. There are other causes of breast and ovarian cancer.

BRCA testing sometimes shows genetic changes that may not be linked to cancer. More research is needed to find out if these changes increase cancer risk.

Should I be tested?

You may have several reasons to have the test:

  • If you test positive, you would consider steps to lower your chance of cancer. These steps might include:
    • For breast cancer, regular clinical breast examinations, mammograms and/or MRIs, taking medicine, or having your breast tissue or ovaries removed.
    • For ovarian cancer, having your ovaries removed after you are done having children, or after age 35.
  • You would feel anxious not knowing if you have a higher chance of cancer.
  • You have a family history of breast or ovarian cancer. The chance is highest if you have two or more close relatives (mother, sister, or daughter) who have had breast or ovarian cancer, especially at a young age.
  • You are of Ashkenazi (Eastern European) Jewish ancestry, with a personal or family history of breast or ovarian cancer. This group has a higher chance of having a BRCA gene change.
  • Your provincial health plan or private insurance covers some or all of the cost of testing.
  • If you test positive, you want to alert other family members (such as a sister or daughter) so they may consider having the test.

Why would I not be tested?

You may have several reasons not to have the test:

  • You may face difficult emotions. You may be afraid and anxious if you test positive. You may feel guilty if you test negative and someone in your family tests positive.
  • You are concerned about how the results might affect your relationships. You have to decide if you would tell a family member—a sister or daughter, for example—who then has to decide if he or she wants to have the test.
  • Your provincial health plan or private insurance does not cover the testing, or covers only some of it. Genetic testing can be very expensive (several hundred to several thousand dollars). But most provincial health plans and private insurance plans will cover the cost of genetic testing for those who meet the conditions for testing.
  • You are concerned about how the information might affect your life, disability, or long-term care insurance. The discovery of a genetic disease that is not causing symptoms now (such as breast cancer) should not affect your future ability to gain employment or health insurance coverage. But it may affect your ability to gain some types of private insurance coverage, such as life insurance, disability insurance, or long-term care insurance.
  • You would not take preventive steps—such as regular examinations and tests, taking medicine, or having your breasts or ovaries removed—no matter what the test results are.

Other Places To Get Help

Organizations

Genetics Home Reference, U.S. National Library of Medicine
8600 Rockville Pike
Bethesda, MD  20894
Phone: 1-888-FIND-NLM (1-888-346-3656)
Fax: (301) 402-1384
TDD: 1-800-735-2258
Web Address: www.ghr.nlm.nih.gov
 

The Genetics Home Reference provides information on hundreds of genetic conditions. The website has many tools for learning about human genetics and the way genetic changes can cause disease. It also has links to additional resources for people who have genetic conditions and for their families.


U.S. National Cancer Institute (NCI)
6116 Executive Boulevard
Suite 300
Bethesda, MD  20892-8322
Phone: 1-800-4-CANCER (1-800-422-6237)
Web Address: www.cancer.gov (or https://cissecure.nci.nih.gov/livehelp/welcome.asp# for live help online)
 

The U.S. National Cancer Institute (NCI) is a U.S. government agency that provides up-to-date information about the prevention, detection, and treatment of cancer. NCI also offers supportive care to people who have cancer and to their families. NCI information is also available to doctors, nurses, and other health professionals. NCI provides the latest information about clinical trials. The Cancer Information Service, a service of NCI, has trained staff members available to answer questions and send free publications. Spanish-speaking staff members are also available.


References

Citations

  1. National Cancer Institute (2009). BRCA1 and BRCA2: Cancer risk and genetic testing. Available online: http://www.cancer.gov/cancertopics/factsheet/Risk/BRCA.

Credits

By Healthwise Staff
Primary Medical Reviewer Joy Melnikow, MD, MPH - Family Medicine
Specialist Medical Reviewer Douglas A. Stewart, MD - Medical Oncology
Last Revised October 26, 2009

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.