Overexpression of cyclooxygenase‐2 is associated with chemoradiotherapy resistance and prognosis in esophageal squamous cell carcinoma patients

Our objective was to investigate whether cyclooxygenase‐2 (COX‐2) expression can predict the patient's response to chemoradiotherapy (CRT) and ensuing prognosis in esophageal squamous cell carcinoma (ESCC). The clinicopathological and follow‐up data of 112 patients with ESCC who underwent CRT from January 2001 to June 2006 were analyzed retrospectively. The immunohistochemical expression level of COX‐2 was examined for all biopsy specimens of primary tumors, and the correlation of COX‐2 expression with the patient's response to CRT and prognosis was examined. COX‐2 positive immunostaining was detected in 111 (99.1%) of the patients, including overexpression in 54 (48.2%) patients and low expression in 58 (51.8%) of the patients. The response of tumors with a low level expression of COX‐2 (70.7%, 41/58) was significantly higher than that of tumors with COX‐2 overexpression (42.6%, 23/54; P = 0.003). Patients with a low level of COX‐2 expression had a higher downstaged rate than those with a high level of COX‐2 expression (9/13 vs 2/8), but the difference was not statistically significant (P = 0.08). In the definitive CRT group (91 cases), COX‐2 overexpression was significantly associated with poor 3‐year overall survival (P = 0.028). Multivariate analysis showed that only metastatic stage (nonregional node metastasis) was an independent prognosis factor. The assessment of COX‐2 status may provide additional information to identify ESCC patients with poor chances of response to CRT and potential candidates for more individualized treatment.