CXCR1 and colorectal cancer: The concentrations of CXCR1/2 ligands CXCL2, CXCL5, CXCL6, and IL-8 were increased in the peripheral blood of patients with stage IV colorectal cancer (one-way ANOVA, CXCL2 control vs stage IV, p = 0.0306; CXCL5 stage I vs stage IV, p = 0.0312; CXCL6 stage I vs stage IV, p = 0.0370; IL-8 control vs stage IV, p = 0.0038) (Figure 3A), suggesting that advanced colorectal cancer recruits a large number of neutrophils to the TME.