What is Cancer?
We are made from millions of tiny cells. As we grow, cells keep on dividing and increasing in number. Most of our cells stop dividing when we stop growing. Some cells keep on dividing for the whole of our lives, so that things get replaced when they are worn out.
Cancer is caused by cells in our bodies continuing to divide when they should have stopped. The dividing cells create a lump that is called a tumor. There are two types of tumors. A benign tumor is harmless and does not spread. A malignant tumor is cancerous and can grow into body parts nearby so that it can be difficult and sometimes impossible to remove. It can also spread because bits can break off and grow in different parts of the body. Sometimes a cancer is not a lump, but faulty cells in the bone marrow or lymph nodes.