In TNM stage III-IV, the proportion of CC genotype at−735 (C/T) locus of MMP-2 gene and TT genotype at −1562 (C/T) locus of MMP-9 gene in patients with lymph node metastasis was higher than that in TNM stage I-stage II patients without lymph node metastasis (P < 0.05) as shown in Table 4. Here, MMP9 is linked to metastatic malignant neoplasm in the lymph nodes.