Genetic Testing for Hereditary Breast and Ovarian Cancer

Genetic testing is available for hereditary breast and ovarian cancer. Most breast and ovarian cancer is not caused by inherited mutations, so genetic testing will not help most women with a family health history of breast and ovarian cancer. Genetic testing will not identify the cause for some hereditary breast and ovarian cancers, because the genes affected in these cancers are not yet known.

Genetic testing for hereditary breast and ovarian cancer looks for mutations in the BRCA1 and BRCA2 genes. Your doctor might suggest testing using a multigene panel, which looks for mutations in several genes at the same time, including BRCA1 and BRCA2. If you are of Ashkenazi Jewish or Eastern European ancestry, your doctor might suggest testing for three specific BRCA1 and BRCA2 mutations, called founder mutations. These are the most common mutations in people of Ashkenazi Jewish or Eastern European ancestry.

The genetic counselor can help you determine the best testing strategy for you and your family. Whenever possible, the first person tested in your family should be someone who has had breast, ovarian, or another BRCA-related cancer. If none of your family members who have had one of these cancers are available for genetic testing, then genetic testing can start with an unaffected person. However, the test results might not be as helpful.

Genetic counseling after genetic testing is important to help you understand your test results and decide the next steps for you and your family:

• If you have a positive test result, the test showed that you have a mutation known to cause hereditary breast and ovarian cancer.
  •  What it means for you
    • You can take steps to make it less likely that you will get cancer or to find cancer early if you do get it.
    • If you have already had breast or ovarian cancer, a positive test result can help guide your treatment decisions.
  • What it means for your family
    • If other family members decide to get genetic testing, their test should check for the same mutation you have.
    • Your parents, children, sisters, and brothers each have a 1 in 2 (50%) chance of having the same mutation.
• If you have a negative test result, the test didn’t find a mutation. However, what this means for you depends on whether you have already had breast or ovarian cancer and whether another relative is known to have a mutation.
  • If you have already had breast or ovarian cancer
    • What it means for you
      • A negative result means that the test did not find a mutation that caused your cancer.
      • Further testing might be available.
    • What it means for your family
      • The breast and ovarian cancer in your family is less likely to be due to an inherited mutation, unless another relative is known to have a mutation.
      • Genetic testing in your family members who have not had breast or ovarian cancer is unlikely to be helpful, unless another relative is known to have a mutation.
      • In some cases testing might still be helpful for another family member who has had breast or ovarian cancer. This is because it is still possible that there is an inherited mutation in your family, but you did not inherit it.
  • If you have not had breast or ovarian cancer
    •  What it means for you
      • If a mutation has not already been found in another family member
        • A negative test result is considered uninformative because the result could mean that
          • the breast and ovarian cancers in your family are caused by one of the mutations included in the genetic test but you did not inherit the mutation,
            OR
          • the breast and ovarian cancers in your family were not caused by a mutation that was included in the genetic test.
        • You are still considered at increased risk for the cancers that run in your family. The level of risk, appropriate screening and prevention options, and need for additional genetic testing will vary for each person and each family.
      • If a mutation has already been found in another family member and the test showed you do not have the mutation
        • You are not at higher risk than the average person for breast or ovarian cancer. You also cannot pass the mutation on to your children.
• If you have a variant of uncertain significance (VUS) result, the test found a mutation in one of the genes associated with hereditary breast and ovarian cancer, but whether that specific mutation causes cancer is unknown. Some mutations prevent genes from working properly, while others have no effect. It is not always easy to tell whether or not a mutation in a gene has a harmful effect.
  • What it means for you
    • If you have already had breast or ovarian cancer, it is unclear whether the mutation found in the test caused your cancer. Further testing might be available.
    • Whether or not you have already had breast or ovarian cancer, you are still considered at increased risk for the cancers that run in your family. The level of risk, appropriate screening and prevention options, and need for additional genetic testing will vary for each person and each family.

Having a strong family health history of breast and ovarian cancer does not mean that you definitely have an inherited mutation. In fact, most women identified as being at increased risk for BRCA1 and BRCA2 mutations based on family health history do not have BRCA1 or BRCA2 mutations.

Using family health history information will not find everyone with BRCA1 or BRCA2 mutations. Not everyone with a BRCA1 or BRCA2 mutation has a strong family health history of breast and ovarian cancer. Some even have no known family health history of breast and ovarian cancer.

Read more about medical options for women with BRCA1 and BRCA2 mutations.

Learn more about the types of family health history risk categories for which genetic testing may be appropriate and about genetic counseling for hereditary breast and ovarian cancer.

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