Genetics – breast cancer in the family
In a small number of cases, breast cancer runs in the family. Of all women who develop breast cancer, about one in five has a significant family history of the disease and about one in 20 has inherited a fault in a gene linked with breast cancer.
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The cells in our bodies each contain thousands of genes, which we inherit from our parents. These provide instructions to tell our cells how to function. People who have inherited faults in known breast cancer genes – such as BRCA1 or BRCA2 – have an increased risk of developing breast cancer.
People with a family history of breast cancer tend to have an unusually high number of close relatives (parents, siblings or children) on one side of the family with breast cancer and/or relatives who developed breast cancer at a young age. Other factors that are considered in determining a family history are cases of ovarian cancer, male breast cancer, cancer in both breasts or having an Ashkenazi Jewish ancestry. When thinking of family history, you should look at your mother’s and father’s sides of the family separately. See How we define a family history for more information.
If you have a family history of breast cancer, you may be at increased risk of developing the disease. Women with a particularly strong family history have a high risk of breast cancer and could have inherited BRCA1 or BRCA2 faults that run in their family.
If you have concerns about any cancers in your family, see your doctor. He or she will ask you about any cancers in your family to work out whether your family history suggests you have an increased risk of breast cancer and help you consider the best options for you. If your doctor feels you may be at increased risk, he or she may refer you to a genetics clinic or family history clinic for specialist care.
But remember, four out of five breast cancers are not related to inherited factors. Having one relative who was diagnosed with breast cancer over the age of 40 would usually not be enough to suggest you might be at increased risk.
For more on services for people with a family history of breast cancer see our our web section on family history or read The best treatment: Your guide to UK services for people with a family history of breast cancer.
Information last reviewed: 1 November 2011
