Some types of cancer can run in families. For example, your risks of developing certain types of breast cancer, bowel cancer or ovarian cancer are higher if you have close relatives who developed the condition.
This doesn’t mean you'll definitely get cancer if some of your close family members have it, but that you may have an increased risk of developing certain cancers compared to other people.
It’s estimated that only about 2 or 3 in every 100 cancers (2-3%) are associated with an inherited faulty gene.
Cancers caused by inherited faulty genes are much less common than those caused by other factors, such as ageing, smoking, being being overweight and not exercising regularly, or not eating a healthy, balanced diet. Most cancers develop as a result of a combination of risk factors, which in some cases can include family history.
It's only likely that a cancer gene is present in a family if:
- there are two or more close relatives on the same side of the family (your mother’s or your father’s side) with the same type of cancer, or with particular types of cancer that are known to be linked – for example, breast and ovarian cancer or bowel and womb cancer
- cancers are occurring at young ages (before the age of 40)
- a close relative has had two different types of cancer (rather than one cancer that has spread)
You should contact your doctor if some close family members have developed the types of cancer mentioned above and you’re worried that you might develop cancer yourself. They'll ask about your family history, and if they think there's a chance you have an increased risk of developing cancer, they'll refer you to a genetic counsellor, family cancer clinic or a cancer specialist.