Cancer is a group of over 200 diseases involving abnormal (malignant) growth of cells that invade organs and tissues and potentially spread (metastasis) to other parts of the body.
A fast, uncontrollable division of those cells leads to the formation of malignant tumors (a cluster of cancerous cells).On the other hand, a benign tumor is simply a localized mass of cells with a slower growth rate. They usually bear a resemblance to the tissue of origin and hardly ever represent risk of death.
The many types of cancer are defined by the many types of body cells they are related to. For instance, when the cancer begins in epithelial lining tissue, of the skin or mucosas, it’s called a carcinoma (very rare in children); if it starts in connective tissue, like a bone, muscle or cartilage, it’s called a sarcoma (more common in children).
Among other aspects that can distinguish the types of cancer from each other, we can mention growth rate and the potential to spread to adjacent or distant (metastasis) tissues and organs.