Pharmacological strategies and micrometastasis: what is known? What must be done?

Metastasis accounts for over 90% of cancer patient deaths. In spite of this , the majority of the currently used drugs are aimed at eradicating or controlling the primary tumor. Hardly any cancer therapies used at the moment interfere only with metastasis and there is a need for drugs acting specifically on the metastatic processes, curing the minimal residual disease and being less toxic than the current drugs. Searching for drugs that do not affect the growth of the primary tumor but inhibit the colonization and/or the outgrowth in distant sites could lead to new drugs specifically aimed at treating the minimal residual disease. The aim of this work is to search at what conditions such drugs might be discovered and if some exist already. For that, mechanisms of actions of current experimental and clinical antimetastatic drugs are described and their utility for different clinical settings (primary prevention, adjuvant setting) is analyzed. In conclusion, clues exist that specific antimetastatic drugs could exist and will be developed in a near future.