CSF-1, which is highly expressed in several types of solid tumor, plays a significant role in the recruitment of peripheral blood monocytes to the tumor microenvironment, differentiation into macrophages, and polarization of macrophages toward an M2-like phenotype via binding to CSF-1R, which is a tyrosine kinase receptor that is highly expressed in circulating monocytes and macrophages [11,12,25,63,64]. The gene discussed is CSF1R; the disease is neoplasm.