Cancer occurs when, for
unknown reasons, cells divide without control or order. All
parts of the body ar
e made up of cells that normally divide
to produce more cells only when the body needs them. When
cancer occurs, cells keep dividing even when new cells are
not needed. The change from normal to cancerous cells requires
several separate, different gene alterations. Eventually uncontrolled
growth from altered genes may produce a tumor that can be
benign (not cancer) or malignant (cancer). Malignant tumors
can invade, damage, and destroy nearby tissues and spread
to other parts of the body. A benign tumor won't spread to
other parts of the body, but local tissue may be damaged and
the growth may need to be removed.
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