[Research progress on tumor-associated macrophages in colorectal cancer]

Colorectal cancer is a common malignant tumor in gastrointestinal tract. Its onset and development are associated with its own characteristics as well as the tumor microenvironment (TME) in which tumor-associated macrophages (TAMs) are the most abundant immune cells. After being recruited to the tumor site and stimulated by different signals in TME, TAMs can grow into two different subtypes, namely M1 and M2. TAMs are mainly manifested as M1 macrophages in the early stage of colorectal cancer, mediating the immune response to inhibit tumor growth. In the late stage, TAMs mainly grow into M2 macrophages, showing the ability to suppress immunity, stimulate the proliferation of tumor cells and tumor angiogenesis, and promote the invasion and metastasis of tumor cells. It has been found that intervention in TAMs polarization can regulate its relationship with the onset and development of colorectal cancer.