Fig. 1 .

Schematic representation of tumor development process (TDP). During TDP, the cancer cells within the primary tumor achieve some sort of capabilities to strike the neighboring tissue (1: progression). The cancerous cells after destructing the ECM get into the lymphatic and blood vessels (2: intravasation), traverse through the vessels (3: dissemination), leave the traveling vessels (4: extravasation), negotiate with the new microenvironment, survive and proliferate (5: dormancy) forming micrometastatic secondary tumor (colonization). EMT: epithelial–mesenchymal transition. MET: mesenchymal–epithelial transition.