In the current study, a total of 22 case-control studies with 8202 cases and 7578 controls were included in the meta-analysis12, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, and the association between MMP1-1607 1G/2G, MMP2-1306 C/T, MMP2-735 C/T, MMP9 -1562 C/T and MMP13 -77A/G polymorphisms and lung cancer risk was explored. The gene discussed is MMP9; the disease is lung cancer.