Cancer is growth of abnormal cells that encroaches on the normal functioning of an organ. The body’s normal mechanisms to control cell growth are not able to control the cancerous cells. The cancer cells grow rapidly and multiply to form a “clump” or mass of cancerous tissue, also known as a tumour. As the tumour enlarges, parts can break off and spread around the body to affect other organs. Common places for cancer to spread include the lungs, liver, bone and brain.