Clinicopathologic significance of cyclooxygenase-2 overexpression in colorectal adenocarcinoma

Background and aim: Cyclooxygenase-2 (COX-2) plays an important role in colorectal cancer development and is frequently up-regulated in colorectal cancer. The purpose of this study was to investigate COX-2 overexpression in colorectal adenocarcinoma and to evaluate the correlation with the clinicopathological parameters and p53 expression, as well as its effect on patient survival. Methods: We evaluated the expression of COX-2 and p53 on the tissue microarray of 414 colorectal adenocarcinomas by immunohistochemistry. Data was analyzed by Fisher's exact test, ��2-test, one-way ANOVA, Cox regression hazards model and log-rank test with Kaplan-Meier curves. Results: The cytoplasmic COX-2 overexpression was detected in 56.3% of colorectal adenocarcinoma samples. COX-2 overexpression was correlated with favorable clinicopathologic factors in lymph node metastasis (P= 0.002), American Joint Committee on Cancer and Dukes' stage (P= 0.008 and P= 0.017, respectively), and lymphatic invasion (P= 0.001). Other characteristics associated with COX-2 overexpression were colonic site of tumor (P= 0.008) and poor differentiation (P= 0.017). There was no correlation between COX-2 overexpression and p53 expression (P= 0.485). In univariate survival analysis, patients with COX-2 overexpression revealed better overall survival and disease-free survival (P= 0.021 and P= 0.017, respectively, log-rank test). In multivariate survival analysis with the Cox proportional hazards model, COX-2 overexpression was an independent prognostic factor of overall survival and disease-free survival (P= 0.029 and P= 0.039, respectively). Conclusions: COX-2 overexpression was significantly associated with favorable clinicopathologic phenotype and an indicator of better survival in our cohort of colorectal cancer patients. �� 2010 The Korean Society for Cytopathology, The Korean Society for Legal Medicine, The Korean Society of Oral and Maxillofacial Pathology, The Korean Society of Pathologists, The Korean Society of Toxicological Pathology, The Korean Society of Veterinary Pathology and Blackwell Publishing Asia Pty Ltd