CXCR4 and cancer: Table 2 reports a detailed description of the clinico-pathological characteristics of the patients and tumors according to CXCR4 expression in the selected studies. In a pooled analysis, significant associations were found between positive or high or strong expression of CXCR4 and T stage > 3 (cancer growing outside the muscularis propria) (P = 0.0001), and positive or high or strong expression of CXCR4 and left-side primary tumor localization (P = 0.0186) (Table S3).