Cancercells are cells gone wrong in other words, they no longer respond to
many of the signals that control cellular growth and death. Cancer cells
originate within tissues and, as they grow and divide, they diverge ever
further from normalcy. Over time, these cells become increasingly resistant to
the controls that maintain normal tissue and as a result, they divide more rapidly
than their progenitors and become less dependent on signals from other cells.
Cancer cells even evade programmed cell death, despite the fact that their
multiple abnormalities would normally make them prime targets for apoptosis. In
the late stages of cancer, cells break through normal tissue boundaries and
metastasize to new sites in the body.