The purpose of this study was to determine the expression of cyclooxygenase-2 (COX-2) in normal epithelium, dysplasia and squamous cell carcinoma of the hypopharynx and to investigate associations with clinicopathological factors and survival. Seventy-five patients with hypopharyngeal squamous cell carcinomas (HPSCC) who underwent surgical treatment at the Department of Otolaryngology, Osaka Medical Center for Cancer and Cardiovascular Diseases, were investigated. COX-2 expression was determined by immunohistochemistry and 97.3% (73/75) of samples displayed immunostaining in tumor cells. COX-2 staining was localized mainly in the cytoplasm (73/75) and was rare in stromal cells (2/75). Over half of the areas of dysplastic cells adjacent to carcinomas also showed COX-2 staining (41/70, 58.6%). There were no significant correlations between the COX-2 expression and tumor size, location and tumor growth type, T- and N-stage, tumor recurrence, lymph node metastasis and survival in this study. COX-2 expression thus does not appear to have a prognostic significance for hypopharyngeal SCC although there was a tendency for higher values in T3/T4 than T1/T2 cases. Furthermore, COX-2 was found to be more strongly expressed in poorly-differentiated than in moderately/well-differentiated carcinomas. In this study group, COX-2 was up-regulated not only in SCCs but also in the dysplastic lesions of the hypopharynx, suggesting that COX-2 inhibition may be a useful chemopreventive strategy.

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