Cancer is the uncontrolled growth of abnormal cells anywhere in the body. These cells are termed as cancer or malignant or tumor cells. These cells infiltrate the normal body cells and tissues, show uncontrolled division and growth and as a result a mass of cells develop. Cancerous cells then break away from the original mass of cells, travel through the blood and lymph systems and get accumulated in other organs of the body where they again repeat the uncontrolled growth cycle. This process of leaving an area and growing in another area of the body is termed as metastasis.