Cancer is a general name for more than 100 diseases in which abnormal cells grow out of control; a malevolent tumor. Cancer is a class of diseases in which uncontrolled cell division invades other tissues, either by direct growth into adjacent tissue (invasion) or by migration of cells to distant sites (metastasis). This unregulated growth is caused by a series of acquired or inherited mutations to DNA within cells, damaging genetic information that define the cell functions and removing normal control of cell division.

Cancer usually develops when cells in a part of the body begin to grow out of control. Though there are many kinds of cancer, they all start because of out-of-control growth of abnormal cells.

Normal body cells grow, divide, and die in an orderly fashion. During the early years of a person's life, normal cells divide more rapidly until the person becomes an adult. After that, cells in most parts of the body divides only to replace worn-out or dying cells and to repair injuries but as cancer cells continue to grow and divide, they are different from normal cells. Instead of dying, they outlive normal cells and continue to form new abnormal cells

Because cancer cells continue to grow and divide, they are different from normal cells. Instead of dying, they outlive normal cells and continue to form new abnormal cells.

There are six main types of treatment for cancer and these are described below. It is fairly common for a combination of treatments to be used.

. Active surveillance (or watchful waiting)
. Surgery
. Radiotherapy
. Chemotherapy
. Hormonal therapy
. Biological therapy