What is cancer?

Cancer is a disease caused by normal cells changing so that they grow in an uncontrolled way.

Normally, cells grow and divide to form new cells, as and when the body needs them. When cells grow old and die, new cells take their place.

Sometimes this orderly process goes wrong - normal cells change and grow in an uncontrolled way. New cells form when the body does not need them, and old cells don’t die when they should. They form a lump or mass called the primary cancer or primary tumour.