An immunohistochemical comparison of endometrial polyps from postmenopausal women exposed and not exposed to HRT

Our study set out to test the null hypothesis that oestrogen containing continuous combined hormone replacement therapy (HRT) would not affect the hormone receptor expression (oestrogen and progesterone receptors-ER, PR) or markers of cell proliferation/apoptosis (Ki67 and Bcl-2) in endometrial polyps from postmenopausal women exposed and not exposed to HRT.

Immunohistochemical staining for ER, PR, Ki67 and Bcl-2 was performed on polyps obtained from two groups of postmenopausal women.

Polyps were obtained from postmenopausal women attending an outpatient hysteroscopy clinic in a district general hospital (Bradford Royal Infirmary, UK).

Twenty-five postmenopausal women presenting with abnormal bleeding subsequently diagnosed with endometrial polyps (16 from women not exposed to HRT, 9 from women exposed to HRT).

Semiquantitative immunohistochemistry was performed.

Significant differences or correlations in either hormone receptor expression or markers of cell proliferation/apoptosis between the two groups of polyps.

There were no significant differences for hormone receptor expression (ER and PR) between endometrial polyps exposed and not exposed to HRT. Bcl-2 expression was higher than Ki67 in both groups, but polyps from HRT users had increased levels reflecting decreased apoptosis in these polyps.

HRT has no demonstrable effect on polyp ER and PR expression. However, HRT does appear to inhibit apoptosis and cell proliferation in endometrial polyps, which may affect polyp growth.