The objective of this study was to re-examine polymorphisms in the genes encoding the gelatinases MMP-2 and MMP-9 at positions -735C/T (rs2285053) and -1562C/T (rs3918242), respectively, and their potential effects on lung cancer, with our rationale for conducting this research being that our understanding of lung cancer has improved over the last decade. The gene discussed is MMP9; the disease is lung cancer.