Cyclooxygenase-2 expression in medullary thyroid carcinoma

BACKGROUND: Recent studies have demonstrated that cyclooxygenase-2 (COX-2) expression is associated with the carcinogenesis of numerous neoplasms. The aim of this study was to evaluate the role of COX-2 in medullary thyroid carcinoma (MTC). METHODS: Tissue specimens of thyroid neoplasms were obtained from 22 patients with MTC and 15 control subjects with nonmalignant thyroid specimens. RESULTS: This immunohistochemical study confirms the presence of COX-2 in a significant number of MTCs. A large area of staining was noted in only 2 patients in the control group (13%) compared with 18 (82%) in the medullary carcinoma group. On a scale of 0 to 3, the average area of positive staining measured 2.35 in the study group and 0.9 in the control group (p < .0001). The average intensity of staining on a scale of 0 to 5 (deep brown) was 2.15 and 0.8 mm, respectively (p < .001). CONCLUSION: COX-2 is expressed significantly in MTC including a larger area of staining and greater intensity than in nonmalignant thyroid tissue. These findings may have important treatment implications for the use of COX-2 inhibitors in patients with MTC.