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BRCA1 and BRCA2 gene testing

Description

The BRCA1 and BRCA2 gene test is a blood test that can tell you if you have a higher risk of getting cancer. The name BRCA comes from the first two letters of breast cancer.

What is the BRCA Gene Mutation?

BRCA1 and BRCA2 are genes that suppress malignant tumors (cancer) in humans. When these genes change (become mutated) they do not suppress tumors like they should. So people with BRCA1 and BRCA2 gene mutations are at a higher risk of getting cancer.

Women with this mutation are at higher risk of getting breast cancer or ovarian cancer. Mutations may also increase a woman's risk of developing:

  • Cervical cancer
  • Uterine cancer
  • Colon cancer
  • Pancreatic cancer
  • Gallbladder cancer or bile duct cancer
  • Stomach cancer
  • Melanoma

Men with this mutation are also more likely to get cancer. Mutations may increase a man's risk of eveloping:

  • Breast cancer
  • Pancreatic cancer
  • Testicular cancer
  • Prostate cancer

Only about 5% of breast cancers and 10 to 15% of ovarian cancers are associated with BRCA1 and BRCA2 mutations.

Who Should Think About Being Tested?

Before being tested, you should speak with a genetic counselor to learn more about the tests, and the risks and benefits of testing.

If you have a family member with breast cancer or ovarian cancer, find out if that person has been tested for the BRCA1 and BRCA2 mutation. If that person does have the mutation, you might consider getting tested, too.

Someone in your family may have the BRCA1 or BRCA2 mutation if:

  • Two or more close relatives (parents, siblings, children) have breast cancer before the age of 50
  • A male relative has breast cancer
  • A female relative has both breast and ovarian cancer
  • Two relatives have ovarian cancer
  • You are of Eastern European (Ashkenazi) Jewish ancestry, and a close relative has breast or ovarian cancer

You have a very low chance of having the BRCA1 or BRCA2 mutation if:

  • You do not have a relative that had breast cancer before the age of 50
  • You do not have a relative that had ovarian cancer
  • You do not have a relative that had male breast cancer

How is the Test Done?

Before the test is done, speak to a genetic counselor to decide whether to have the test.

  • Bring with you your medical history, family's medical history, and questions.
  • You might want to bring someone with you to listen and take notes. It is hard to hear and remember everything.

If you decide to be tested, your blood sample is sent to a lab that specializes in genetic testing. That lab will test your blood for the BRCA1 and BRCA2 mutations. It can take weeks or months to get the test results.

When the test results are back, the genetic counselor will explain the results and what they mean for you.

What Does a Positive Test Result Mean?

A positive test result means you have inherited the BRCA1 or BRCA2 mutation.

  • This does not mean you have cancer, or even that you will get cancer. This means you are at a higher risk of getting cancer.
  • This also means you can or could have passed this mutation on to your children. Each time you have a child there is a 1 in 2 chance your child will get the mutation you have.

When you know you are at higher risk of developing cancer, you can decide if you will do anything differently.

  • You may want to be screened for cancer more often, so it can be caught early and treated.
  • There may be medicine you can take that could reduce your chance of getting cancer.
  • You may choose to have surgery to remove your breasts or ovaries.

None of these precautions will guarantee you will not get cancer.

What Does a Negative Test Result Mean?

If your test result for the BRCA1 and BRCA2 mutations is negative, the genetic counselor will tell you what this means. Your family history will help the genetic counselor understand a negative test result.

A negative test result does not mean you will not get cancer. It may mean you have the BRCA1 or BRCA2 mutation, but the test results were not clear. It may mean you have the same risk of getting cancer as people who do not have this mutation.

Be sure to discuss all results of your tests, even negative results, with your genetic counselor.

References

BRCA and BRCA2: Cancer Risk and Genetic Testing. National Cancer Institute Web site. Last reviewed April 15, 2015. www.cancer.gov/cancertopics/factsheet/Risk/BRCA. Accessed October 7, 2015.

BRCA-Related Cancer: Risk Assessment, Genetic Counseling, and Genetic Testing. U.S. Preventive Services Task Force Web site. Current as of July 2015. www.uspreventiveservicestaskforce.org/uspstf/uspsbrgen.htm. Accessed October 7, 2015.

Gordon OK. Cancer of the breast and female reproductive tract. In: Rimoin D, Korf B, eds. Emery and Rimoin's Principles and Practice of Medical Genetics. 6th ed. Philadelphia, PA: Elsevier; 2013:chap 89.


Review Date: 8/1/2015
Reviewed By: Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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