PTGS2 and non-small cell lung carcinoma: When all of the predictors were included in a multivariate analysis, COX-2 expression in tumor tissue retained a significant association with both VEGF expression and MVD (hazard ratio, 9.836; P = 0.001; hazard ratio, 3.147; P = 0.025), demonstrating that COX-2 expression in tumor tissue is an independent predictive factor of VEGF expression and MVD in NSCLC patients.