Cancer is a group of many related diseases. All forms of cancer involve the out-of-control growth and spread of abnormal cells. Normal body cells grow, divide, and die in an orderly fashion. During the early years of a person's life, normal cells divide more rapidly until the person becomes an adult. After that, normal cells of most tissues divide only to replace worn-out or dying cells and to repair injuries. Cancer cells, however, continue to grow and divide, and can spread to other parts of the body. Cancer cells may accumulate and form tumors (lumps) that may compress, invade, and destroy normal tissue. It is important to know that all tumors are not cancerous. Noncancerous tumors are called benign tumors.
You can learn much more at our Online Cancer Center.