Cell cycle analysis and detection of proliferative cell nuclear antigen of the endometrium after hormone replacement therapy

Background: To understand the effect of sequential combined hormone replacement therapy (HRT) on the postmenopausal endometrium. Methods: Sonographic endometrial thickness, endometrial histopathology, flow cytometric cell cycle analysis and the level of proliferative cell nuclear antigen (PCNA) were studied. Results: One hundred and thirty-eight postmenopausal women were enrolled in this study. Among which, 97 women had their endometrium being adequately obtained; the most frequent type of histopathology was normal endometrium (91.8%). Endometrial hyperplasia was found in seven patients (7.2%), including typical simple hyperplasia (n=1, 1%), focal simple hyperplasia (n=5, 5.2%) and complex hyperplasia without atypia (n=1, 1%). The proliferative fractions (PF; S plus G₂–M phase) of cells from normal and hyperplastic endometrium of menopausal women after HRT were 8.18 and 8.95%, respectively, which were lower than those from 29 premenopausal women without HRT. The level of PCNA of normal and hyperplastic endometrium in postmenopausal women after HRT was about 80 and 84%, respectively, of that from premenopausal endometrium. Conclusions: Our study showed the PF of the cell cycle and the level of PCNA were not increased in the menopausal endometrium under HRT as compared to the premenopausal controls.