Cancer
is really a group of diseases. There are more than 100 different types of
cancer, but they all are a disease of some of the body's cells.
Healthy
cells that make up the body's tissues grow, divide, and replace themselves
in an orderly way. This process keeps the body in good repair. Sometimes,
however, normal cells lose their ability to limit and direct their growth.
They divide too rapidly and grow without any order. Too much tissue is
produced and tumors begin to form. Tumors can be either benign
or malignant.
Benign
tumors are not cancer. They do not spread to other parts of the body and
they are seldom a threat to life. Often, benign tumors can be removed by
surgery, and they are not likely to return. Malignant tumors are cancer.
They can invade and destroy nearby tissue and organs. Cancer cells also
can spread, or metastasize, to other parts of the body, and form
new tumors.
Because
cancer can spread, it is important for the doctor to find out as early as
possible if a tumor is present and if it is cancer. As soon as a diagnosis
is made, treatment can begin.