This week's artwork was donated by Jaclyn, a pediatric cancer patient who received treatment at The Children's Hospital of Philadelphia .
Cancer is a disease in which certain cells begin to divide too quickly and without any order.
Cancer cells can also spread through the bloodstream and the lymph system to other parts of the body to form new tumors. Cancer that started in one place, but has spread to another part of the body is called metastatic cancer. Squamous cells line the outside of many body organs, including the mouth, nose,skin, throat, and lungs. Lymph nodes are small bean-shaped structures that are found throughout the body. They produce and store infection-fighting cells.