Cyclooxygenase-2 expression in endometrial carcinoma: correlation with clinicopathologic parameters and clinical outcome

BACKGROUND: Cyclooxygenase-2 (COX-2) is overexpressed in endometrial hyperplasia and carcinoma, but no data have been reported until now about the expression of COX-2 and its possible clinical significance in endometrial carcinoma. We investigated by immunohistochemistry the expression of COX-2 in a single institutional series of primary untreated endometrial carcinoma patients. The relationship between COX-2 expression and microsatellite instability (MI) status was also analyzed. METHODS: The study was conducted on 69 primary untreated endometrial carcinoma patients who were admitted to the Department of Obstetrics and Gynecology, Catholic University of Rome. Immunohistochemistry was performed by using rabbit polyclonal antiserum against human COX-2. Analysis of MI was performed for 47 patients with endometrial carcinomas. RESULTS: Twenty-seven patients (39.1%) were scored as COX-2 positive. COX-2 positivity was higher (60.8%) in endometrial carcinoma with cervical or extrauterine involvement than in tumors limited to the corpus (28.3%; P = 0.0174). COX-2 positivity increased from Grade 1 (13.6%) to Grade 2 (41.7%) to Grade 3 (60.9%) endometrial carcinoma (P = 0.0049). Interestingly, considering early International Federation of Gynecology and Obstetrics stage patients (n = 53), the percentage of COX-2 positivity was higher in patients with deep myometrial invasion (66.7%) than in patients without or less than 50% myometrial invasion (15.6%) (P = 0.0003). No association between COX-2 and MI status was found. COX-2-positive patients showed a trend to a shorter disease-free survival than COX-2-negative patients (P = 0.09). CONCLUSIONS: COX-2 is expressed in a high percentage of a large series of primary endometrial tumors and its expression may be associated closely with parameters of tumor aggressiveness The possible prognostic role of COX-2 in endometrial carcinoma deserves further study.