WHAT CAUSES CANCER?

One of the most common questions that people ask is "What causes cancer? " Most peoples' knowledge about cancer comes from either friends' experiences or what they have heard on TV or read in the papers. In this section we will try to sort out the facts from the fiction.

THE FACTS

* As cancer is not one but many diseases, what causes one type of cancer doesn't necessarily cause another. For example, smoking is the main cause of lung cancer but not of breast cancer.
* Experts agree that most cancers are caused by our bodies, or parts of them, being exposed to certain substances over long periods of time. These cancer-causing substances are called carcinogens.
* For example, people who smoke have a lot more of certain types of cancers than non-smokers. There are also differences between countries. For example, in Japan the death rate from stomach cancer is about twice that for England and Wales, while the death rate from breast cancer is about six times lower.
* These community studies, together with laboratory and other scientific experiments have shown us the causes of at least some forms of cancer in humans. Smoking is by far the most important preventable cause of cancers.

VIRUSES: Viruses are tiny particles which can reproduce only inside living cells. They can spread between people in a number of ways – in the ar or in the blood, for instance.

Cancers where viruses are thought to play a role include cervical cancer, cancer of the liver and a skin cancer that can develop in people with AIDS. Cervical cancer is associated with a virus that can be transmitted through sexual intercourse. Cancer of the liver can develop in a person who has had an attack of hepatitis B – a virus which can be transmitted through sexual intercourse or using infected needles, e.g. illegal drug use.

Experts have estimated that more than 80% of cancers may be avoidable through changes that can be made in lifestyle and in the environment. In the following pages this booklet shows you the kind of changes that you can make reduce your risk of getting certain cancers.