Different coexisting endometrial histological features in asymptomatic postmenopausal breast cancer patients treated with tamoxifen.

In an attempt to assess the hypothesis that different endometrial sites may respond differently to tamoxifen exposure in postmenopausal women, hysteroscopic selected endometrial histology was investigated in 175 postmenopausal breast cancer patients who received continuous treatment with tamoxifen, and in 27 similar patients not treated with tamoxifen who served as controls. In the tamoxifen-treated patients 14 (8.0%) developed endometrial polyps. Of 14 patients, 8 (57.2%) each displayed atrophic endometrium in the same histologic specimen, 5 (35.7%) each had coexisting simple hyperplasia, and 1 (7.1%) other had complex hyperplasia. Another 21 (12.0%) developed simple or complex hyperplasia. The endometrial hyperplasia coexisted with atrophic endometrium in all these patients. All these lesions were selectively identified by hysteroscopic examination prior to the endometrial biopsy. In the control group 3 (11.0%) had simple hyperplasia and 2 (7.4%) had endometrial polyps. The above results support the hypothesis that the endometrium of postmenopausal breast cancer patients on tamoxifen treatment may possess different responses to tamoxifen exposure.