Univariate analyses showed that T classification (P = 0.034), lymph node metastases (P < 0.01), clinical stage (P < 0.01), HIF-1α expression (P < 0.01) and MMP-13 expression (P < 0.01) were all significantly correlated with patients’ survival (Table 2). This evidence concerns the gene MMP13 and metastatic malignant neoplasm in the lymph nodes.