We did not detect a statistically significant difference in MMP-7 protein expression between adenocarcinoma patients and squamous cell carcinoma patients (P = 0.273), and MMP-7 protein expression in lung cancer patients with LN metastasis was significantly higher than that in patients without LN metastasis (OR = 2.81, 95% CI: 1.73-4.58, P <0.001). Here, MMP7 is linked to squamous cell carcinoma.