Does tamoxifen therapy affect the hormone receptor expression and cell proliferation indices of endometrial polyps?: An immunohistochemical comparison of endometrial polyps from postmenopausal women exposed and not exposed to tamoxifen

ObjectiveThis study set out to test the null hypothesis that tamoxifen therapy would not affect the hormone receptor expression (oestrogen and progesterone receptors—ER and PR) or markers of cell proliferation/apoptosis (Ki67 and Bcl-2) of endometrial polyps from postmenopausal women exposed and not exposed to tamoxifen.MethodsEndometrial polyps were prospectively obtained from women presenting with abnormal bleeding attending an out-patient hysteroscopy clinic who subsequently underwent endometrial polypectomy (16 from postmenopausal women not exposed to tamoxifen, 9 from women exposed to tamoxifen). Immunohistochemical staining for ER, PR, Ki67 and Bcl-2 was performed on polyps from both groups of women. Non-parametric statistical analysis was used (Mann–Whitney and Spearmans rank correlation).ResultsEndometrial polyps from tamoxifen users had significantly lower oestrogen receptor but increased progesterone receptor and Bcl-2 expression. There were no significant differences for proliferation markers (Ki67) between postmenopausal endometrial polyps exposed and not exposed to tamoxifen.ConclusionsTamoxifen has a significant affect on hormone receptor expression and markers of apoptosis in endometrial polyps. The results support the hypothesis that tamoxifen promotes polyp growth by inhibiting apoptosis. The mechanism for this does not appear to be oestrogen receptor mediated.