This week's artwork was donated by Vansom, a pediatric cancer patient who received treatment at The Children's Hospital of Philadelphia .
Cancer is a group of many different diseases that have some important things in common.
Cancer affects our cells, the body's basic unit of life. To understand cancer, it is helpful to know what happens when normal cells become cancerous. The body is made up of many types of cells. Normally, cells grow, divide, and produce more cells as they are needed to keep the body healthy. The mass of extra cells forms a growth or tumor.