|| Cisplatin is used to treat lung cancer;however, it is also a known carcinogen. Cyclooxygenase-2 (COX-2) inhibitors have been shown to prevent carcinogen-induced experimental tumors. We investigated
the effect of a COX-2 inhibitor, celecoxib, on cisplatin-induced lung tumors. One hundred twenty 4-week-old A/J mice were divided into 6 groups:group 1, no treatment;group 2, low-dose celecoxib (150mg/kg);group 3, high-dose celecoxib (1,500mg/kg);group 4, cisplatin alone;group 5, cisplatin plus low-dose celecoxib;and group 6, cisplatin plus high-dose celecoxib. Mice in groups 4-6 were administered cisplatin (1.62mg/kg, i.p.) once a week for 10 weeks between 7 and 16 weeks of age. All mice were sacrificed at week 30. Tumor incidence was 15.8% in group 1, 25% in group 2, 26.3% in group 3, 60% in group 4, 50% in group 5, and 50% in group 6. Tumor multiplicity was 0.2, 0.3, 0.3, 1.3, 1.0, and 0.6 in groups 1-6, respectively. Tumor multiplicity in the cisplatin-treated mice was reduced by celecoxib treatment in a dose-dependent manner (p＜0.05, group 4 vs. group 6). Celecoxib significantly reduced COX-2 expression in cisplatin-induced tumors (p＜0.01, group 4 vs. group 6).