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
How cancer spreads
A malignant tumour is made up of cancer cells. When it first develops, this malignant tumour may be confined to its original site, a cancer in situ (or carcinoma in situ). If these cells are not treated they may spread beyond their normal boundaries and into surrounding tissues (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 breast cancer spreads to the bone, it is called a bone secondary (or metastasis). Your cancer doctor will still refer to it as breast cancer even though it has spread to another organ.
The sort of treatment you are given for cancer depends on the type of cancer, where it began, and whether it has spread. Your cancer doctor will also take into account individual factors such as your age and general health.
Treatments for cancer include surgery, chemotherapy (drug treatment), hormone treatment, or radiation treatment. Monoclonal antibodies, which are now used to treat a few 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.