By ELISA, the concentration of CXCL1 was found to be significantly higher in plasma samples of ESCC patients (n=35) compared with that in healthy controls (n=29), suggesting CXCL1 may serve as a potential tumor biomarker of ESCC patients (P=0.04207; Figure 7a). This evidence concerns the gene CXCL1 and esophageal squamous cell carcinoma.