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Family history - when cancer runs in the family

Our risk of cancer is influenced by the genes we inherit from our parents. If you are born with certain faulty genes then you may be more likely to develop cancer.

There are many different causes of cancer and having a certain gene will not definitely mean that you develop the disease. Only around 5-10 per cent of cancers are thought to be caused by faulty inherited genes.

Reducing your risk of cancer

If you do have a family history of cancer then you can receive special advice and may be offered screening to assess your risk.

If you are adopted or don't know about cases of cancer in your family try not to worry. Remember that changes to your lifestyle may have more effect on your cancer risk than your genes.

How do I know if I am at risk?

There is a possibility that cancer may run in your family if on one side of the family:

• there are several cancers of the same type
• there are several cases of rare cancers
• members developed cancer before the age of 50
• members developed multiple cancer tumours (for example in both breasts)

Certain types of cancers are known to run together. These include:

• breast and ovarian cancer
• bowel, uterus, ovary and stomach cancer

Different types of genes

Scientists have identified a few rare 'high risk' genes that can cause many cases of cancer in one family. We now think that there are also 'moderate' and 'low' risk genes that may also cause cancer in families and can skip generations.

What should I do if I’m worried?

If you are worried about your family history of cancer then you should visit your GP. Your doctor will either reassure you that you are not at particularly high risk, or refer you to a clinical genetics centre.

Clinical genetics centres

In the UK there are 26 NHS clinical genetics centres, most with an associated family cancer clinic. If your doctor refers you to a clinical genetics centre they will asses your risk based on the details of your family history. The clinic will be able to tell many people that they are not at high risk of cancer at this stage.

If the clinic thinks you are at a high risk of cancer, they will discuss this with you and help you examine your options. Options may include genetic testing, increased screening and cancer prevention advice.