Cyclooxygenase-2 expression in the endometrium at the end of 2 years' continuous combined hormone replacement therapy

Objective: To evaluate the change of endometrial histology and the expression of cyclooxygenase-2 (Cox-2) in the endometrium after continuous combined hormone replacement therapy (HRT). Methods: Forty-five postmenopausal women were recruited. All participants received 0.625 mg conjugated equine estrogen (CEE) and 2.5 mg medroxyprogesterone (MPA) daily for 2 years. Endometrial biopsy was performed twice, before medication (baseline) and after 2 years of HRT, respectively. Immunohistochemistry was used to detect the presence of Cox-2 expression. Results: More atrophic and weak secretory features of endometrium were noted after the 2-year HRT. Endometrial hyperplasia and carcinoma were not found and immunohistochemistry results revealed that Cox-2 was not expressed in the endometrium. Conclusion: Cox-2, known to play an important role in the tumorigenesis of cancer, was not stained in endometrium tissue after hormonal induction and more endometrium atrophy was noted after the 2-year HRT. From the results, it is noted that continuous combined HRT may be a relatively safe and appropriate regimen for long-term use in postmenopausal women.