MMP9 and lung cancer: When we carried out the stratified analysis by selected variables, an association was found between the polymorphism in the MMP9 gene and the lung cancer risk for age and smoking status (adjusted OR = 0.07; 95% CI: 0.01-0.58; and adjusted OR = 0.28; 95% CI: 0.08-1.01, respectively) [Data not shown].