An abnormal growth of cells which tend to proliferate in an uncontrolled way and, in some cases, to metastasize (spread)Cancer is not one disease. It is a group of more than 100 different and distinctive diseases.
Cancer can involve any tissue of the body and have many different forms in each body area. Most cancers are named for the type of cell or organ in which they start. If a cancer spreads (metastasizes), the new tumor bears the same name as the original (primary) tumor.