Our findings demonstrated that +837 T > C (rs5275) polymorphism in COX-2 elevates the susceptibility to oral cancer and there were significant statistical differences in gene frequencies between the case and control groups in both allele model and dominant model (allele model: RR = 0.87, 95% CI = 0.77~0.98, P = 0.021; dominant model: RR = 0.53, 95% CI = 0.40~0.72, P < 0.001) (Figure 3, Table 2). This evidence concerns the gene PTGS2 and lip and oral cavity carcinoma.