Cancer develops when cells in a part of the body begin to grow out of control. While normal cells grow, divide and die in an orderly fashion, cancer cells outlive normal cells and continue to form new abnormal cells. Cancer cells develop because of damage to the DNA — a substance found in every cell that directs all of the cell’s activities.

Cancer arises out of normal cells in the body, and can develop in almost any organ or tissue, such as the lung, colon, breast, skin, bones, or nerve tissue. There are many types of cancer, which behave differently and respond to different treatments.

Cancer treatments can cause potentially serious side effects, such as neutropenia (a decrease in infection-fighting white blood cells), anemia (a decrease in oxygen-carrying red blood cells), and severe oral mucositis (a condition causing painful mouth ulcerations).