BRCA1 & BRCA2

How common are BRCA1 and BRCA2 mutations?

  • In the general population, between one in 300 and one in 800 individuals carry a BRCA1 or 2 or mutation.1,3
  • For individuals of Ashkenazi Jewish ancestry, one in 40 individuals carry a BRCA1 or 2 mutation.

What percentage of breast and ovarian cancers are caused by BRCA1 or BRCA2 mutations?

  • 5 percent-10 percent of all breast cancer.
  • Up to 15 percent of ovarian cancers.1-4

What are the lifetime cancer risks associated with BRCA1 and BRCA2 mutations?

  • Breast cancer: 44 percent-87 percent
  • Ovarian cancer: 20 percent-50 percent
  • Male breast cancer and pancreatic cancer: ~7 percent

Which patients should I refer to a genetic counselor for risk assessment and discussion of genetic testing for BRCA1 and BRCA2 mutations?

Patients who have a personal or family history (this includes maternal or paternal lineages) or those who have had:1-3,5

  • Breast cancer at a young age (younger than age 50)
  • Ovarian cancer at any age
  • Bilateral breast cancer or 2 or more primary tumors of the breast
  • Breast and ovarian cancer
  • Breast cancer and are male
  • Two or more biological relatives* on the same side of the family with breast and/or ovarian cancer (*parent, child, siblings, grandparent, grandchild, aunt/uncle, niece/nephew, first cousin)
  • Breast or ovarian cancer and are of Ashkenazi Jewish ancestry
  • Confirmed BRCA1 or BRCA2 mutation in their family

Specific indications for genetic counseling and testing vary among professional organizations. The indications above are to be used as a guide and are not a substitute for clinical judgment. Not all clinical scenarios can be anticipated such as when there is a limited family structure or family medical history.

What are the benefits of genetic counseling when offering BRCA1 and BRCA2 testing?

  • Patient education and informed consent are critical aspects of the genetic testing process and will help individuals decide if genetic testing is right for them.
  • Pre-test counseling addresses the implications of potential test results, medical management options, psychosocial challenges, laws protecting against genetic discrimination, other options for testing and testing costs. Examples include:
    • The possibility of false negative results because genes other than BRCA1 and 2 may be responsible for cancers in the family
    • The possibility of test results with mutations noted to have “uncertain clinical significance”
    • The cost of BRCA gene testing differs depending on which level of testing is indicated ($440-$3,770)
    • The possibility of indirectly disclosing non-paternity, non-disclosed adoptions or use of egg or sperm donation
  • If help is needed, a genetics health care professional also can provide assistance with dissemination of relevant information to at-risk family members.

Resources

Genetics health care professionals:

BRCA1 and BRCA2 referral, testing and risk management guidelines:

Patient friendly facts about genetic testing for breast and ovarian cancer risk

References

  1. Berliner, J.L. et al. (2007) Risk assessment and genetic counseling for hereditary breast and ovarian cancer: Recommendations of the National Society of Genetic Counselors. Journal of Genetic Counseling. 16:241-260.
  2. U.S. Centers for Disease Control and Prevention. Located September 4, 2009, at http://www.cdc.gov/genomics/training/perspectives/factshts/breastcancer.htm
  3. National Cancer Institute. Genetic Testing for BRCA1 and BRCA2: It’s Your Choice. Located September 4, 2009, at http://www.cancer.gov/cancertopics/factsheet/Risk/BRCA/print?page=&keyword
  4. Pinsky, L.E., et al. (2001) Why should primary care physicians know about breast cancer genetics? Western Journal of Medicine. 175:168-173.
  5. Guidelines listed in Resources above.