From Table 2, data showed that MMP-9 expression in cancer tissues was significantly associated with age (P = 0.044), pathological classification (P = 0.002), depth of invasion (P < 0.001), lymph node metastasis (P < 0.001), distant metastasis (P < 0.001) and TNM stage (P < 0.001). This evidence concerns the gene MMP9 and metastatic malignant neoplasm in the lymph nodes.