The word cancer actually refers to many diseases, not one. In fact, there are more than 100 types of diseases known collectively as cancer. What they all have in common is the overgrowth of cells, tiny units that make up all living things. Cancer (also known as malignancy, pronounced: muh-lig-nun-see) occurs when cells begin to grow and multiply in an uncontrolled way.
Normal body cells grow and divide over a period of time until they eventually die. But cancer cells continue to grow and divide and grow and divide. Eventually, they gather to form tumors. Tumors (pronounced: too-murz) are lumps that can interfere with the body’s normal processes. Sometimes cells from a tumor break away and travel to a different tissue or organ. This is called metastasis (pronounced: muh-tas-tuh-sus).
As scary as all this sounds, most cancers can be treated and controlled and many people with cancer get better and lead normal lives.