[The physiopathology of metastases: from primary to secondary]

Metastasis genesis is the result of a series of many steps which make a tumoral cell localised in a primary tumor move and graft onto another organ to form a new tumor. Tumoral cells must go through the following steps: primary tumor formation, proliferation and angiogenesis, deep tissue invasion and arrival in the circulatory system, preparation for travel, migration, embolization in an organ, attachment to the wall of blood vessel, exit from the vessel, adaptation to the micro-surrounding, anchorage and neo-angiogenesis which corresponds to the metastasis establishment. At each step, there are defence and regulation mechanisms which, when they fail, lead to metastatic dissemination.