Macrophage depletion significantly reduced leptin-induced tumor volume (P < 0.05, Figure 6A) and tumor weight (P < 0.01, Figure 6C), improved survival (P < 0.05, Figure 6D), attenuated leptin-mediated exacerbation pulmonary metastasis (P < 0.01, Figure 6E), and decreased leptin-stimulated expression of IL-8 and Ki67 in the tumor (P < 0.05, Figure 6G). This evidence concerns the gene CXCL8 and neoplasm.