RESUMEN
OBJECTIVES: To evaluate the histologic effects of tamoxifen on the endometrium using hysteroscopy in postmenopausal women with breast cancer. METHODS: The study included 46 postmenopausal patients who were referred from another clinic due to thickening or bleeding of the endometrium after taking tamoxifen for breast cancer. All patients underwent transvaginal sonography (TVS) and hysteroscopic endometrial biopsy with a 5-mm, continuous-flow, operating hysteroscope. RESULTS: The incidence of malignancy was high (20%) in cases of abnormal uterine bleeding (AUB) after taking tamoxifen. However, in the non-AUB group with thick endometrium after taking tamoxifen, the incidence of adenocarcinoma was 3.2%. CONCLUSIONS: Our findings confirm the estrogen-like effect of tamoxifen on the endometrium. Endometrial evaluation with TVS suggests further diagnostic procedures; moreover, histologic examination is necessary under hysteroscopy, especially in cases of endometrial bleeding after taking tamoxifen.