This metastasis-associated CD11b+macrophage population is different from the classically defined inflammatory Gr1+CCR2+CX3CR1low macrophages and Gr1-CCR2-CX3CR1high tissue macrophages [62] and is also distinct from other recently identified macrophage populations in the primary tumor microenvironment such as myeloid suppressor and pro-angiogenic macrophages [11], [63], 64. Here, CCR2 is linked to neoplasm.