Of all women who develop breast cancer, about 1 in 5 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, e.g. 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.
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 inherited, lifestyle and environmental factors can play a role.
Most cases of breast cancer are not familial 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
