Cancer is the name given to a collection of related diseases. In all cancer types, the body’s cell begins to divide out of control and spread into surrounding tissues. Cancer can start almost anywhere in the human body, which is made up of trillions of cells. In normal cases, human cells grow and divide to form new cells as the body needs them. When cells grow old or become damaged, they die and a new cell takes their place. When cancer develops, however, this process of cell creation breaks down. As the cells become more abnormal, leaving old or damaged cells to survive when they should die, they allow new cells to form when they are not needed. These extra cells divide without stopping, ultimately causing the growth of a cancerous tumor.