What Is Cancer?

Cancer is the name for diseases in which the body's cells become abnormal and divide without control. Cells are the very small units that make up all living things, including the human body. There are billions of cells in each person's body.

Normal body cells grow and divide and know to stop growing. Over time, they also die. Cancer occur when cells that are not normal grow and spread very fast. Unlike these normal cells, cancer cells just continue to grow and divide out of control and don't die when they're supposed to.

Cancer cells usually group or clump together to form tumors. A growing tumor becomes a lump of cancer cells that can destroy the normal cells around the tumor and damage the body's healthy tissues.

Sometimes cancer cells break away from the original tumor and travel to other areas of the body, where they keep growing and can go on to form new tumors. This is how cancer spreads. The spread of a tumor to a new place in the body is called metastasis.