Expression of Cyclooxygenase-2 in Well Differentiated Thyroid Carcinoma

ABSTRACT

PURPOSE: Several reports have suggested that the expressing of COX-2 is related to carcinogenesis and the prognosis of cancer. The aim of this study was to discover the relationship between the prognostic factors of a differentiated thyroid carcinoma (DTC) and the rate of COX-2 expression. METHODS: We performed immunohistochemical staining on well conditioned thyroid cancer paraffin specimens obtained from the patients that had undergone a thyroidectomy at the Department of Surgery, Chungbuk National University Hospital during 1994. The specimens were composed of papillary carcinomas (n=23), follicular carcinomas (n=9) and follicular adenomas (n=4). We analyzed the expressions of COX-2 in relation to age, distant metastasis, invasion to extrathyroidal tissue, mass size and risk group. A statistical analysis was performed using the Chi-square, Fishers Exact, and Mantel- Haenszel Chi-Square tests on the PC SAS system. RESULTS: COX-2 was expressed in 82% of the papillary carcinomas (19/23), 33% of the follicular carcinomas (3/9) and none of the follicular adenomas (0/4). There were no significant differences between the expression of COX-2 in all the items compared (P-value>0.05) i.e. age, distant metastasis, invasion to extrathyroidal tissues, mass size or risk group. CONCLUSION: COX-2 was expressed in 82, and 33% of the papillary and follicular carcinomas, respectively. The papillary carcinomas had a higher rate of expression than the follicular carcinomas, but this was not significantly correlated with the clinical and prognostic parameters. These results suggested that COX-2 might not be a prognostic factor in DTC.