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www.cancercharity.org
About Cancer
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Cancer is a group of more than 100 different diseases. Cancer occurs when cells become abnormal and keep dividing and forming more cells without control or order. All organs of the body are made up of cells. Normally, cells divide to produce more cells only when the body needs them. This orderly process helps keep us healthy. If cells keep dividing when new cells are not needed, a mass of tissue forms. This mass of extra tissue, called a growth or tumour, can be benign or malignant. Benign tumours are not cancer. They can usually be removed and, in most cases, they do not come back. Most important, cells from benign tumours do not spread to other parts of the body. Benign tumours are rarely a threat to life. Malignant tumours are cancer. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumour and enter the bloodstream or the lymphatic system. This is how cancer spreads from the original (primary) tumour to form new tumours in other parts of the body. The spread of cancer is called metastasis. Most cancers are named for the type of cell or the organ in which they begin. When cancer spreads, the new tumour has the same kind of abnormal cells and the same name as the primary tumour. For example, if lung cancer spreads to the liver, the cancer cells in the liver are lung cancer cells. The disease is called metastatic lung cancer (it is not liver cancer). Cancer develops gradually as a result of a complex mix of factors related to environment, lifestyle, and heredity. Scientists have identified many risk factors that increase the chance of getting cancer. They estimate that about 80 percent of all cancers are related to the use of tobacco products, to what we eat and drink, or, to a lesser extent, to exposure to radiation or cancer-causing agents (carcinogens) in the environment and the workplace. Some people are more sensitive than others to factors that can cause cancer. |