Sarah Cannon - October 26, 2015

When Angelina Jolie opted to undergo a double mastectomy after genetic testing revealed she carried the BRCA1 gene, it sparked a lot of conversations. Many now wonder what genetic testing would reveal about their own risks. Learn more about the BRCA mutations and guidelines for genetic testing.

About BRCA1 and BRCA2

Both BRCA1 (on chromosome 17) and BRCA2 (on chromosome 13) are human genes that, when functioning normally, produce proteins that help repair damaged DNA and manage a cell’s genetic stability.

However, if either gene is mutated or altered, these proteins either aren’t made or fail to function correctly, which can prevent DNA damage from being repaired. This can increase the risk of the cells developing additional genetic alterations that can lead to cancer.

Cancers Linked to BRCA1 and BRCA2 Mutations

According to the National Cancer Institute , female breast and ovarian cancers (both hereditary and non-hereditary), have been linked to specific mutations in BRCA1 and BRCA2 with 20 to 25 percent of hereditary breast cancers driven by the mutations and about five to 10 percent of all breast cancers and 15 percent of ovarian cancers linked to BRCA1 and BRCA2 mutations.

Lifetime risks for developing breast cancer for those who have inherited BRCA1 and BRCA2 mutations include:

  • 55 to 65 percent of women with the inherited BRCA1 mutation will develop breast cancer by age 70.
  • 45 percent of women with the inherited BRCA2 mutation will develop breast cancer by age 70.

The risk for developing ovarian cancer is lower but still important to monitor. Lifetime risks are as follows:

  • 39 percent of women with the inherited BRCA1 mutation will develop ovarian cancer by age 70.
  • 11 to 17 percent of women with the inherited BRCA2 mutation will develop ovarian cancer by age 70.

It is estimated that 12 percent of women in the general population will develop breast cancer sometime in their lives and 1.3 percent of women will develop ovarian cancer.

Risk Factors for BRCA Mutations

Certain factors can increase the risk of carrying a BRCA mutation:

  • Genetics - If either parent carries the BRCA mutation, the child has a 50 percent chance of inheriting the mutation.
  • Ethnic origins - Statistically speaking, those of Ashkenazi Jewish descent, as well as Norwegian, Dutch and Icelandic nationalities, are more likely to have BRCA1 or BRCA2 mutations.
  • Family history - Having first or second degree relatives with breast or ovarian cancer can increase the likelihood of the presence of the BRCA1 or BRCA2 mutations.

Genetic Testing for BRCA Mutations

The United States Preventive Services Task Force has made the following recommendation for women considering genetic testing for BRCA mutations:

  • Women who have family members with breast, ovarian, fallopian tube or peritoneal cancer should be screened to see if their history is associated with an increased risk of carrying a BRCA mutation. If so, then genetic counseling is recommended to determine if BRCA testing would be useful.
  • Women whose family history is not associated with increased risk for BRCA mutations do not need routine genetic counseling or BRCA testing.

Several different types of genetic testing methods are available to detect the BRCA mutations- some look the mutations in one of the genes and others check for all possible mutations in both genes. The samples for testing typically involve DNA extracted from blood or saliva, and usually take about one month for results.

Sarah Cannon HCA Midwest Health offers cancer genetic risk assessments and genetic counseling to women who have concerns about their personal and/or family history of cancer. Patients are provided with personalized information regarding genetic influences, specific cancer risks and targeted screening and prevention options.

Learn more about genetic counseling and HCA Midwest Health's counselors here .

Sources:

Medline Plus: Genetic Counseling

Medline Plus: Genetic Testing

National Cancer Institute BRCA1 and BRCA2: Cancer Risk and Genetic Testing fact sheet

National Human Genome Research Institute: Frequently Asked Questions About Genetic Testing

National Human Genome Institute: National Guidelines and Recommendations

U.S. Preventive Services Task Force: Risk Assessment, Genetic Counseling, and Genetic Testing for BRCA-Related Cancer in Women (PDF)

Sarah Cannon HCA Midwest Health