What is cancer?

Cancer is a disease of the body’s cells. It starts in our genes. Our bodies are constantly making new cells: to enable us to grow, to replace worn-out cells or to heal damaged cells after an injury. All cancers are caused by damage to some genes.

This damage usually happens during our lifetime, although a small number of people inherit a damaged gene from a parent when they are born. Normally, cells grow and multiply in an orderly way. However, damaged genes can cause them to change. They may grow into a lump which is called a tumour.

The beginnings of cancer


Tumours can be benign (not cancerous) or malignant (cancerous). Benign tumours do not spread to other parts of the body.

How cancer spreads


A malignant tumour is made up of cancer cells. When it first develops, a malignant tumour may be confined to its original site. If these cells are not treated they may spread beyond their normal boundaries and into surrounding tissues which is called invasive cancer.

Sometimes, cells move away from the original (primary) cancer through the blood or lymphatic systems and invade other organs. When these cells reach a new site they may form another tumour. This is called a secondary cancer or metastasis. For example, if prostate cancer spreads to the bone, it is called a bone secondary (or metastasis).

Your cancer doctor will still refer to it as prostate cancer even though it has spread to another part of your body.

The sort of treatment you are offered for cancer depends on the type of cancer, where it began and whether it has spread.

Your cancer doctor will also take into account other things about you, such as your age and general health.

Treatment for cancer includes surgery, radiation treatment, hormone treatment or chemotherapy (drug treatment).

Immune therapy or targeted treatments, which are now used to treat some cancers, will become increasingly important in the future.

Sometimes only one of these methods of treatment is used for a cancer. Sometimes more than one is used.