The role of tumor associated macrophages in the tumor microenvironment: Mechanism and functions

During tumor progression, several types of inflammatory cells are recruited into the tumor site, where they participate in tumor-associated inflammation, such as fibroblasts, granulocytes, lymphocytes and macrophages. Macrophages infiltrating into the tumor microenvironment are termed tumor-associated macrophages (TAMs). In response to multiple stimuli, macrophages undergo recruitment and polarization, and play an important role in further tumor development. In this article, we present a review of the mechanism of macrophage’ recruitment, and the role that TAMs play in promoting immunosuppression, tumor progress and metastasis, as well as chemoresistance and future therapeutic strategies.