Cancer is a group of diseases in which the genetic controls that
regulate the normal proliferation of the body’s cells become
disabled, and the cells begin to divide chaotically, at an
accelerated pace. In time, they amass into a lump of excess
tissue called a tumor. A tumor that does not invade normal
tissue is said to be benign. It is not cancerous. Aside from
tumors embedded in the brain, most benign growths can be removed
surgically without incident. Invasive tumors are cancerous. If
not treated successfully, these malignant masses will continue
to enlarge and possibly spread to other parts of the body. The
tumor can extend through one organ and into another, or a colony
of cells from the primary tumor may break off and travel the
circulatory system to seed a secondary tumor a distance away.
The medical term for this is metastasis. It is important to keep
in mind that cancer is identified according to the original
location and cell type. A colon tumor that metastasizes to the
liver is not the same disease