Tumor cells not only secrete high levels of colony-stimulating factor 1 (CSF-1) to independently recruit macrophages (Zhu et al., 2014) but also release the chemokine CCL2 in conjunction with Schwann cells, facilitating the infiltration of inflammatory monocytes via the CCL2/CCR2 axis (Sanford et al., 2013; Bakst et al., 2017). This evidence concerns the gene CCL2 and neoplasm.