In the tumor microenvironment, there are many tumor-related immunosuppressive cells, including regulatory T cells (Treg), tumor-associated macrophages (TAM), and myeloid-derived suppressive cells (MDSC), etc. The chemokines in the tumor microenvironment recruit the Tregs in the thymus, bone marrow, lymph nodes, and the periphery to the tumor through the Treg receptor CCR4, thereby suppressing immunity. This evidence concerns the gene CCR4 and neoplasm.