I know I have a family history of breast cancer. Does this mean I have an increased risk for developing breast cancer?

In some families, abnormal genes (or gene mutations) that greatly increase breast cancer risk are passed on from parent to child. It is estimated that 5-10% of all cases of breast cancer are due to hereditary factors.

Researchers have discovered several genes linked to increased breast cancer risk. The most common of these genes are the BRCA1 (breast cancer 1) and BRCA2 (breast cancer 2) genes. About 1 in 200 women in North America carries a BRCA1 or BRCA2 mutation. However, among certain ethnic groups the prevalence is higher. For women of Ashkenazi Jewish ancestry the prevalence is 1 in 50.

Simply having a family history of breast cancer doesn’t necessarily mean you have an increased risk of developing it yourself. Doctors look for certain factors in your family history that may suggest an increased risk for hereditary cancer.

What kind of family history may suggest an increased risk of developing hereditary breast cancer?

A family history that might suggest an increased risk of developing breast cancer would include at least one of the following:

  • You or a family member diagnosed with breast cancer before the age of 50, or ovarian cancer at any age.
  • Two or more relatives on the same side of your family diagnosed with either breast or ovarian cancer.
  • You or a family member diagnosed with breast and ovarian cancer, or breast cancer in both breasts.
  • A male relative diagnosed with breast cancer.
  • Ashkenazi Jewish heritage (Jews of Eastern European descent) with one or more relatives diagnosed with breast or ovarian cancer.
  • A family member with a known gene mutation in BRCA1 or BRCA2.

What should I do if I think my family history puts me at high risk?

If any of these descriptions apply to you or if you are still worried about your family history, talk with your doctor. It’s helpful to collect your family health history and bring it with you. If possible, include the age at which your family members were diagnosed with cancer, as cancers that present at a younger age may suggest a hereditary pattern.

Links to more information

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Genetics of Breast and Ovarian Breast Cancer
Source: National Cancer Institute

Family History and the Risk for Breast or Ovarian Cancer
Source: Health Link BC