Cancer is a disease which occurs when changes is a group of normal cells within the body, lead to uncontrolled growth causing a lump called a tumour; this is true of all cancers except leukaemia (cancer of the blood).
Cancer can start almost anywhere in the human body, which is made up of trillions of cells.
Normally, human cells grow and divide to form new cells as the body needs them. When cells grow old or become damaged, they die, and new cells take their place.
When cancer develops, however, this orderly process breaks down. As cells become more and more abnormal, old or damaged cells survive when they should die, and new cells form when they are not needed. These extra cells can divide without stopping and may form growths called tumours.
Many cancers form solid tumours, which are masses of tissue. Tumours (lumps) can be benign or malignant.
• Benign tumours are not cancerous and rarely threaten life. They tend to grow quite slowly, do not spread to other parts of the body and are usually made up of cells quite similar to normal / healthy cells. They will only cause a problem if they grow very large, becoming uncomfortable or press on other organs – for example a brain tumour inside the skull.
• Malignant tumours are faster growing than benign tumours and have the ability to spread and destroy neighbouring tissue. Cells of malignant tumours can break off from the main (primary) tumour and spread to other parts of the body through a process known as metastasis. Upon invading healthy tissue at the new site they continue to divide and grow. These secondary sit’s are known as metastases and the condition is referred to as metastatic cancer.
Cancer can be classified according to the following categories:
• Carcinoma – A cancer that arises from the epithelial cells (the lining of cells that helps protect or enclose organs). Carcinomas may invade the surrounding tissues and organs and metastasise to the lymph nodes and other areas of the body
• Sarcoma – A type of malignant tumour of the bone or soft tissue (fat, muscle, blood vessels, nerves and other connective tissues that support and surround organs).
• Lymphoma – Lymphoma is a cancer of the lymphatic system, which runs all through the body, and can therefore occur anywhere. The two main forms are non-Hodgkin’s which begins with uncontrolled growth of the – white blood cells -lymphocytes – of the immune system) and Hodgkin’s lymphoma in which cells of the lymph nodes become cancerous.
• Leukaemia – Leukaemia is a cancer of the white blood cells and bone marrow, the tissue that forms blood cells. There are several subtypes; common are lymphocytic leukaemia and chronic lymphocytic leukaemia.
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