A study including 243 NSCLC patients and 350 healthy controls showed that the frequency of the MMP-7 -181G allele in NSCLC patients was significantly higher than that in healthy controls, besides, the -181G allele (A/G + G/G) genotypes significantly increased susceptibility to NSCLC compared with the A/A genotype, with OR=2.00[95% CI = 1.23-3.24] for NSCLC (137) (Table 4).However, in another study, MMP-7 -181 A/G polymorphism was found not significantly associated with LC susceptibility (138) (Table 4). Here, MMP7 is linked to laryngotracheoesophageal cleft.