[ node--page--full.tpl : 'full']
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.
Of these, around a quarter – or 2,400 patients each year – have inherited faults in known breast cancer genes, eg BRCA1 and BRCA2. A further 4,800-7,200 people each year are believed to be affected by other genetic factors linked to breast cancer, but the specific genes involved are not yet known in many cases.
How can breast cancer risk be inherited?
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. 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 there is a history of breast cancer, or some other cancers (especially ovarian cancer) in your family, this may increase your risk of developing the disease, and possibly at a younger age. It doesn’t, however, mean that you’ll definitely get breast cancer. We can’t always say what causes breast cancer or predict who will develop it, but a combination of our genes, lifestyle and life choices and surrounding environments can play a role.
Most cases of breast cancer are not hereditary and occur when there is either no family history or only one case in an older relative, which would be expected to occur by chance.
Information last reviewed: 17 March 2011