The role of inflammation in tumor invasion

While at first inflammatory reactions within the stroma of malignant tumors have been considered as a sign of immunological response to the tumor, there is now ample evidence that inflammation is able to promote tumor progression. It is now clear that tumor cells themselves direct the assembly of tumor stroma, using signalling pathways normally confined to inflammatory cells. By producing inflammatory mediators, tumor cells are able to recruit inflammatory cells to the tumor site, induce myofibroblasts and the production of extracellular matrix components. Paradoxically, the host reaction assists tumor progression by providing optimal conditions for growth and migration of tumor cells. In order to achieve a better understanding of malignant tumor progression, malignant tumors have to be regarded as a complex interactive microecosystem of tumor cells and stromal elements.