TAMOXIFEN MEDIATED HUMAN ENDOMETRIAL CARCINOGENESIS MAY NOT INVOLVE ESTROGENIC PATHWAYS - A PRELIMINARY NOTE

Seven cases of endometrial adenocarcinoma patients who had experienced long-term tamoxifen treatments as adjuvant therapy of breast carcinom a, were investigated with respect to estrogen receptor (ER) status. Fo ur cases of endometrial adenocarcinoma without tamoxifen treatment but with a previous history of breast carcinoma were investigated for com parison. One of the 7 and two of the 4 cases were positive for ER immu nohistochemically. Thus, the frequency of ER positivity in secondary e ndometrial adenocarcinoma seemed to be at random among tamoxifen-treat ed and non-treated br east cancer patients. These results suggest that tamoxifen-mediated human endometrial carcinogenesis may not involve e strogenic pathway(s) but may involve other carcinogenic mechanisms suc h as DNA adduct formation as shown in rat liver tumorigenesis.