Many people who find that they are at an increased risk of getting a particular cancer look for ways of reducing their risk. By looking at large numbers of people, doctors and researchers have found out that certain factors seem to increase a person's risk of developing cancer. These are called risk factors. The best-known risk factor for cancer is smoking. If you smoke, you are at a far higher risk of developing lung cancer, and you also increase your risk of getting other cancers (for example, bladder, bowel or cervical cancer).

Some risk factors have been found to play a role in the development of breast cancer generally – not only for people who have a strong family history of the disease:

• An early first period (menarche) and late menopause seem to slightly increase a woman's breast cancer risk.
• The contraceptive pill and HRT may both slightly increase a woman's risk of breast cancer particularly if taken for more than five years. However, women's individual situations vary and it is important to talk to your doctor about your own particular risk.
• Other risk factors are being very overweight, particularly after the menopause, and drinking large amounts of alcohol.

The following factors seem to lower women's breast cancer risk:

• physical exercise
• a diet high in vegetable and fruit content
• having children early in life and breastfeeding them. However, this factor has been questioned for women who have (carry) a BRCA1 or 2 mutation.

All of the above risk factors also apply to ovarian cancer, except for the contraceptive pill: the pill seems to reduce ovarian cancer risk. If you have a significantly increased breast and ovarian cancer risk in your family (for example, because a BRCA1 or 2 mutation has been found in your family), this can make deciding whether to take the pill difficult. The pill might reduce your ovarian cancer risk but increase your breast cancer risk.

Here are some risk factors for bowel cancer:

• a history of polyps in the bowel or other chronic bowel problems
• a diet containing a lot of fat and meat and not enough fruit and vegetables
• alcohol and smoking.

The following factors can lower your bowel cancer risk:

• a diet high in vegetable and fruit content and low in fat and salt
• regular, moderate physical exercise.

Not all of the factors listed here are within a person's control. It is also not clear how all these different factors might interact. There is also no good evidence about how much these factors affect the small group of people who have a strong family history of cancer. However, some people say that if they avoid some of the above risk factors it makes them feel they are doing whatever they can to control their risk of cancer. If you are thinking about ways of reducing your own cancer risk, it is worth discussing your ideas with your specialist so that you can take into account your personal circumstances.

It is clear that giving up smoking, eating a balanced diet, exercising moderately and maintaining a healthy weight is good for you regardless of your cancer risk and can make you feel better in many ways.