COX2 expression predicts resistance to chemoradiotherapy in esophageal squamous cell carcinoma

The overexpression of cyclooxygenase (COX)2 is correlated with carcinogenesis, tumor progression, and prognosis, and increased COX2 expression is correlated with radiation resistance. However, no correlation between the COX2 expression and resistance to chemoradiotherapy for esophageal squamous cell carcinoma has been characterized. The purpose of the present study was to evaluate whether COX2 expression is an indicator of resistance to chemoradiotherapy in esophageal squamous cell carcinoma and the feasibility of COX2 as a biomarker for CRT.

Fifty-eight patients who were diagnosed with esophageal squamous cell carcinoma from biopsy samples were enrolled in the present series. All patients underwent concurrent chemoradiotherapy in a neoadjuvant setting, followed by radical esophagectomy. COX2 expression was evaluated by immunohistochemical staining and statistically compared with the histopathologic findings in surgically resected specimens.

The rate of responders was 87% for weak expression of COX2, 62% for moderate expression, and 30% for strong expression, and there was a close correlation between COX2 expression and the response rate (Kendall's τb = 0.396, P = 0.001). In the univariate analysis, negative or weak expression of COX2 was found to correlate significantly with CRT response (odds ratio, 6.296; 95% confidence interval (CI), 1.58-25.096; P = 0.010). In the multivariate analysis, weak expression of COX2 (30% or less) was found to be an independent prognostic factor (odds ratio, 6.534; 95% CI, 1.535-27.803; P = 0.011).

The COX2 expression predicts resistance to chemoradiotherapy in esophageal squamous cell carcinoma, and it also is a feasible biomarker for evaluating the CRT response.