Relationship between the sensitivity of neoadjuvant chemoradiotherapy and the expression of cyclooxygenase-2 in locally advanced rectal cancer

Abstract

Objective To investigate the relationship between the sensitivity of neoadjuvant chemoradiotherapy and the expression of cyclooxygenase-2 (COX-2) in locally advanced rectal cancer. Methods Clinicopathologic data of 42 patients with local mid-low advanced rectal cancer receiving preoperational concomitant chemoradiotherapy were retrospectively analyzed. Immunohistochemical assay was performed in pre-chemoradiotherapy specimens to determine the expression of COX-2 protein. Postoperative pathological tissue sections were reassessed for evaluation of tumor regression grade [0-4, complete pathological response (pCR)=4] after radiochemotherapy. The relationship of expression COX-2 with pCR was analyzed by chisquare test. Results Patients with low expression of COX-2 had significantly higher incidence of pCR than those with high expression of COX-2 (63.6% vs. 36.3%). The expression of COX-2 was negatively correlated with pCR (r=-0.762, P=0.019). Patients with high expression of COX-2 had significantly higher expression of VEGF than those with low expression of COX-2 (64.0% vs. 36.0%). The expression of COX-2 was positively correlated with VEGF (r=0.531, P=0.028). The univariate analysis showed that age, gender, distance between tumor and the anal verge, circumferential extent of the tumor, clinical stage and T-staging were not clearly associated with the expression of COX-2 in rectal cancer. Conclusion The expression of COX-2 is associated with efficiency of neoadjuvant chemoradiation of rectal cancer. Key words: Rectal neoplasm; Cyclooxygenase-2; Neoadjuvant chemoradiotherapy; Complete pathological response