Significance of immunohistochemical expression of cyclooxygenase-2 in squamous cell carcinoma of the esophagus

Background: The focus of studies on cyclooxygenase-2 (COX-2) have been on its ability to mediate the biological behavior of human tumors including tumorigenesis, tumor progression, apoptosis, and differentiation. The aim of the current study was to elucidate a further finding on the clinicopathologic significance of immunohistochemical expression of COX-2 in esophageal squamous cell carcinoma (ESCC). Methods: The immunohistochemical expression of COX-2 was examined for 76 specimens of ESCC and the correlation of COX-2 expression with clinicopathologic features was examined. Results: Twenty-eight ESCCs (36.8%) had a strong expression of COX-2. The proportion of poorly differentiated SCCs among tumors with a strong expression of COX-2 (42.8%, 12 of 28) was significantly higher than that among tumors with a weak expression of COX-2 (16.7%, 8 of 48; P =. 037). The depth of the tumors (P =. 003) and the stage of the tumors (P =. 015) were advanced significantly more progressively in ESCCs with a strong COX-2 expression. Univariate analysis showed that the prognosis of patients with ESCCs with a strong COX-2 expression was significantly poorer than that of patients with ESCCs with a weak COX-2 expression (P =. 017). Multivariate analysis showed that only such tumor-related factors as lymphatic invasion (P =. 004), venous invasion (P =. 003), and stage of the tumors (P =. 021) were found to be associated independently with worse prognosis of the patients with ESCC. Conclusions: Strong expression of COX-2 is correlated with tumor progression and poor differentiation in ESCC.