Stratification analysis in this study showed that smoking did not significantly influence the association between the MMP-7-181A/G and NSCLC, and MMP-7-181A/G polymorphism was not associated with lymphatic metastasis in NSCLC patients, indicating that the MMP-7-181A/G polymorphism might not predict lymphatic metastasis in NSCLC (137). This evidence concerns the gene MMP7 and non-small cell lung carcinoma.