MMP13 and lung cancer: Results: The subjects carrying the TT genotype had a decreased risk of lung cancer in MMP9-1562C/T comparing with the CC genotype (p = 0.00, OR = 0.45, 95% CI = 0.29–0.68), and the MMP13-77 AA genotype was associated with a decreased risk of NSCLC by comparing with the GG genotype (p = 0.03, OR = 0.56, 95% CI = 0.33–0.94).