It is not intended to give a comprehensive overview of breast and ovarian cancer genetics on these pages; instead links are provided to relevant websites for further information.  

Breast cancer is a common disease and it is likely that at least 1 in 9 women in the UK will develop it during their lifetime, so it is not unusual for a patient to have one or two relatives who have developed breast cancer by chance. Ovarian cancer is less common, with 1 in 48 women developing ovarian cancer during their lifetime.

The development and progression of both breast and ovarian cancers can involve several factors, such as environmental, lifestyle, reproductive, and genetic factors.

A significant family history

• Breast and ovarian cancers that have occurred in a family are more likely to be significant if:
• There is more than one case of breast cancer on the same side of the family
• The cancers were diagnosed at a young age (e.g. before the menopause)
• The people who have had breast cancer are closely related (first and second-degree) blood relatives of the patient - such as mother, aunt, grandmother, sisters.
• A close relative of the patient has had bilateral breast cancer.
• The patient is of Eastern European and/or Jewish descent.

Cancer susceptibility genes: