METASTISIS

Invasion- in this step primary tumor cells break free from normal molecular restraints.

Transport-  Tumor cells gain access to the bloodstream.  Cancer cells often hitch a ride with platelets, and this allows them to be disguised and avoid immune destruction from phagocytes. 

Extravasation- is the exit of a tumor cell from the blood or lymphatic vessel. 

Metastatic colonization- involving the formation of new blood vessels as an essential process to provide nutrients and oxygen.