Endorsed by the European Oncology Nursing Society

Is my family at risk of breast cancer?

Is my family at risk of breast cancer? image

If you have been diagnosed with breast cancer, it is normal to wonder whether this means that members of your family might have a greater risk of developing it too.

Breast cancer is a complex disease, caused by the interplay of many elements,1 but there are certain established risk factors; these include genetic predisposition.2 Most cases of breast cancer are actually not hereditary, but about 5–10% can be explained through inheritance, i.e. that a gene mutation has been passed on from a parent. 1–3

Your family member’s own risk doubles if they have had a first-degree relative with breast cancer, and increases 5-fold with two first-degree relatives.4 It is important to keep in mind that even if there is a genetic mutation that predisposes you to cancer in your family, it does not necessarily mean that everyone who has inherited the genetic mutation will develop cancer.5

The likelihood of your relatives having an abnormal breast cancer gene is greater if:

  • They have first degree blood relatives who had breast cancer diagnosed before the age of 50 years6
  • Any one person in your family had both breast and ovarian cancer, or cancer in both breasts6,7
  • There are other gland-related cancers in your family6
  • A man in your family has had breast cancer6
  • They are of Ashkenazi Jewish (Eastern European) ancestry6

If you think you might have a genetic risk factor, speak with your doctor about genetic testing. Most inherited forms of breast cancer are associated with one of two genes: BRCA1 and BRCA2.6 Currently, genetic testing can trace the most common mutations in the BRCA1 and BRCA2 genes, as well as some rarer genetic abnormalities.6

Genetic mutations in the BRCA1 or BRCA2 genes have also been linked to an increased risk of cancers such as ovarian cancer or even prostate cancer.7

Having a genetic risk factor does not mean your relatives will be diagnosed with breast cancer, but discussing your concerns with a genetic counsellor can help you take a critical step towards peace of mind. Genetic counselling can help you understand the benefits and limitations of genetic testing, as well as the medical implications of your test results for yourself and your family members.5



  1. Martin AM, Weber BL. Genetic and hormonal risk factors in breast cancer. J Natl Cancer Inst. 2000;92:1126-35.
  2. Breastcancer.org. Factors. Accessed February 2016.
  3. ESMO. BREAST CANCER: A GUIDE FOR PATIENTS. Accessed February 2016.
  4. Breastcancer.org. Family History. Accessed February 2016.
  5. National Cancer Institute. Genetic Testing. Accessed February 2016.
  6. Breastcancer.org. Genetics. Accessed February 2016.
  7. Cancer.org. Heredity and Cancer Accessed February 2016.