What Is the Breast Cancer BRCA Gene Test?

What is the BRCA gene test?

BRCA genes (BRCA 1 and 2) are among the genetic mutations linked to breast cancer, ovarian cancer, and other cancers

  • Every woman with a BRCA mutation is at high risk for breast cancer, irrespective of whether she has a family history of breast cancer or not.
  • By age 80, a woman with a BRCA mutation has about an 80% chance of developing breast cancer.
  • BRCA1 and BRCA2 gene mutations also increase the risk of ovarian cancer, by 54% and 23%, respectively.
  • Inherited BRCA1 or BRCA2 mutations account for 5-10% of all breast cancers. 

What are the purposes of breast cancer BRCA gene test?

Women who have the BRCA gene have an increased risk of developing breast cancer.
Women who have the BRCA gene have an increased risk of developing breast cancer.
  • The BRCA gene test analyses DNA to look for harmful mutations in two breast cancer genes (BRCA1 or BRCA2).
  • Medical professionals perform this test as a routine blood test.
  • The test should only be performed on patients who have specific types of breast cancers or have a family history suggesting the possibility of having an inherited mutation.
  • These mutations are uncommon, and inherited BRCA gene mutations are responsible for about 5%-10% of breast cancers.

Who is a candidate for BRCA gene testing?

Discuss this with your health care provider or treatment team as this information is frequently updated. Guidelines for testing may include the following:

  • A personal history of breast cancer diagnosis at a young age, bilateral breast cancer, breast and ovarian cancer diagnosis, or a personal history of ovarian cancer
  • A personal history of bilateral breast cancer (cancer in both breasts)
  • A personal history of triple negative breast cancer (breast cancer that is estrogen receptor-negative, progesterone receptor-negative and HER2-negative) diagnosed at age 60 or younger
  • Ashkenazi Jewish heritage and a personal history of breast cancer
  • A family history of breast cancer at a young age (under 50) or ovarian cancer and a personal history of breast cancer
  • A person or a family member with bilateral breast cancer, ovarian cancer, or both breast and ovarian cancer
  • A relative with a known BRCA1 or BRCA2 mutation
  • A personal or family history of male breast cancer

There is only a very small chance your family carries a BRCA1/2 mutation if you or a family member is the only person in your family with breast cancer and breast cancer occurred at an older age.

In most cases, genetic testing is not recommended when there is a low chance of finding a mutation.

Most breast cancers are not due to a BRCA1/2 or other inherited gene mutation linked to breast cancer

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What are the risks and benefits of BRCA gene test?

A health care provider or genetic counselor can talk with you about the risks, benefits, and issues you may face when you are considering genetic testing.

Testing for BRCA1 and BRCA2 gene mutations requires a blood or saliva sample.

There can be physical, emotional and financial impacts of knowing your genetic status. That's why testing for a BRCA1/2 mutation is only recommended for people who fall into one of the above guidelines.

Even if it’s recommended, genetic testing is a personal decision. A genetic counselor can help you decide if BRCA1/2 testing is right for you.  

Testing for BRCA 1/2 mutations

In most cases, the person with cancer is tested first.

  • If no BRCA1/2 mutation is found, the cancer was not due to a BRCA1 or BRCA2 mutation.
  • If a BRCA1/2 mutation is found, other family members can be tested for the specific mutation.

Just because one person in the family has a mutation doesn’t mean everyone in the family has the mutation. Only identical twins have the exact same genes. Other family members share some, but not all, of their genes.

For example, if your mother has a BRCA1 mutation, there's a 50 percent chance you will have a BRCA1 mutation (you get half of your genes from your mother and a half from your father).

If your family members with breast cancer or ovarian cancer are deceased or aren't willing to be tested (or if your family medical history is unknown), a genetic counselor can help you decide whether it would be useful to have BRCA1/2 testing.

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Medically Reviewed on 12/11/2019
References
Kroener, L., D. Dumesic, and Z. Al-Safi. "Use of fertility medications and cancer risk: a review and update." Curr Opin Obstet Gynecol May 22, 2017.

Salerno, K.E. "NCCN Guidelines Update: Evolving Radiation Therapy Recommendations for Breast Cancer." J Natl Compr Canc Netw 15(5S) May 2017: 682-684.

Shield, Kevin D., et al. "Alcohol Use and Breast Cancer: A Critical Review." Alcoholism: Clinical and Experimental Research Apr. 30, 2016.
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