As summarized in Table 2, CXCL8 protein expression was significantly correlated with clinical stage (I–IIA compared with IIB–IV; P=0.009), distant metastasis (absent compared with present; P=0.045), histological type (adenocarcinoma compared with squamous cell carcinoma; P<0.001), and histological grade (well compared with moderately/poorly; P<0.001). This evidence concerns the gene CXCL8 and adenocarcinoma.