Cancer is a term used to describe when a cell divides in an abnormal way, resulting in disease. Most cancers are named based on the organ or cell in which they originated, for example cancer that originates in the breast is called breast cancer.
Cancers are generally listed under one of five umbrella categories:
Carcinoma: Cancer that originates in the skin or in the tissue that lines or covers internal organs. There are a number of subtypes of carcinoma including basal cell carcinoma (skin), squamous cell carcinoma (skin), adenocarcinoma (glandular cancer), and transitional cell carcinoma (urinary system cancer).
Lymphoma and myeloma: Cancer that originates in the immune system.
Sarcoma: Cancer that originates in bone, cartilage, fat, muscle, connective or supportive tissue or blood vessels.
Leukaemia: Cancer that originates in blood-forming tissue and causes large numbers of abnormal blood cells to be produced and invade the blood stream.
Central nervous system cancers: Cancer that originate in the brain and/or spinal cord.
The body is made up of many types of cells. These cells grow and divide in a controlled way to produce more cells as they are needed to keep the body healthy. When cells become old or damaged, they die off and are replaced with new cells.
However, sometimes this process goes wrong. In some cases the genetic material of a cell can become damaged, producing an abnormality that affects normal cell growth and division. When this abnormality takes effect, the cells may not die, however new cells are still produced even when the body may not require them. These extra cells may then form an abnormal mass of tissue known as a tumour.
Not all cancers form tumours, such as leukaemia which is a cancer of the bone marrow and blood.
Not all tumours are cancerous. Tumours can be malignant or benign. Malignant tumours are cancerous, benign tumours are not.
In some cases, cells in a malignant tumour can invade nearby tissue and spread to other parts of the body. This is called metastasis.