[Morphologic endometrium changes with tamoxifen]

Women receiving tamoxifen as adjuvant therapy for breast cancer usually develop atrophy of the endometrium. Cystic polyps as well as endocervical and clear-cell metaplasias also frequently arise in the these atrophic endometria. The invasive endometrial carcinomas we have observed in these women have all been until now either mucinous, clear-cell or serous-papillary carcinomas, that is, different from the endometrioid type of adenocarcinomas that arise under estrogenic stimulation. Our histological studies support the assumption that tamoxifen has an antiestrogenic, gestagen-like action on the endometrium; they contradict the premise that tamoxifen therapy exerts an estrogen effect.