In this study, we aimed to i) examine whether COX-2 inhibitor administration successfully suppresses the development of smoking-induced lung cancer using our established mouse model and ii) examine the behavior of the COX metabolic pathway during smoking exposure by lipidomic analysis and elucidate the molecular mechanism of lung-cancer inhibition by examining the function of lipid metabolites through in vitro experiments. The gene discussed is PTGS2; the disease is lung carcinoma.