Cancer is the uncontrolled growth of abnormal cells in the body. In the body, there are trillions of cells with various functions. These cells grow and divide to help the body function properly. Cells die when they become old or damaged, and new cells replace them.
Cancer develops when the body’s normal control mechanism stops working. Old cells do not die and cells grow out of control, forming new, abnormal cells. These extra cells may form a mass of tissue, called a tumor. Some cancers, such as leukemia, do not form tumors.
