Here, we provide evidence that ICAM-1 deficiency accelerates macrophage infiltration and contributes to macrophage polarization toward a pro-tumor M2 phenotype, implying that endogenous ICAM-1 exerts a metastasis suppressor effect in part through inhibiting macrophage recruitment and M2 polarization in the tumor microenvironment. Here, ICAM1 is linked to neoplasm.