Normal body cells grow, divide, and die in an orderly fashion. During the early years of a person's life, normal cells divide more rapidly until the person becomes an adult. After that, cells in most parts of the body divide only to replace worn-out or dying cells and to repair injuries.

Cancer occurs when abnormal cells in the body begin to grow out of control. Instead of dying, they outlive normal cells and continue to form new abnormal cells. As their numbers increase they form a lump or tumour. When cancer cells break away and spread to other parts of the body they may produce secondary tumours known as metastases.

Cancer cells grow out of control because of damage to DNA. DNA is in every cell and directs all its activities.

Most of the time when DNA becomes damaged the body is able to repair it. In cancer cells, the damaged DNA is not repaired.

People can inherit damaged DNA, which accounts for inherited cancers. Many times though, a person's DNA becomes damaged by exposure to something in the environment.

What Causes Cancers?

In many cases, the exact cause of cancer remains a mystery. We know that certain changes in our cells can cause cancer to start, but we don't yet know exactly how this happens. A great deal of research is currently underway studying a number of possible causes.

Cancers tend to occur by chance. This means that the main reason why one person gets cancer and another does not, is bad luck.

Cancers are not infectious nor, for most cancers, is there any evidence that they are inherited. It is exceptionally rare for a second child in a family to develop cancer. Parents often worry that their child has a cancer because of something they did or did not do. This is not the case and parents should not feel guilty or take any sort of blame for their child developing cancer.

Cancer is rare in children. In Malaysia, the incidence of paediatric cancer is about 77.4 per million children aged less than 15 years and these are quite different from cancers affecting adults and they respond differently to treatment. The prospects for many children have improved dramatically with advances in treatment. Cure rates for children are much higher than for most adult cancers and over 60% of all children can now be completely cured. However each type of cancer will have their own cure rate.