CXCR2 and squamous cell carcinoma: In both subgroup analysis of groups with multivariate models, Asian group and small sample size with regard of OS, study by Liang et al. [15] was the source of heterogeneity, which reported that overexpression of CXCR2 was a favorable factor in esophageal adenocarcinoma and squamous cell carcinoma in terms of OS and was contradictory to previous studies.