Interestingly, MMP-7 protein expression in lung cancer patients with lymph node metastasis was significantly higher than in lung cancer patients without lymphatic metastasis, which was not influenced by age (positive: OR = 3.89, 95% CI = 2.27 to 6.67, P <0.001; negative: OR = 1.86, 95% CI = 1.31 to 2.64, P <0.001) (Figure 3). Here, MMP7 is linked to lung cancer.