All organs of the body are made of cells. Normally, these cells divide to produce more cells only when the body needs. Cancer occurs when these cells become abnormal and keep dividing without control or order. Therefore, cancer can affect any organ in the body.

"Cancer" is composed of more than 100 different disease types. Some of the most common types of cancer are discussed under "Types of Cancer". To learn more about some of these common cancer diseases, select the appropriate link.