ABSTRACT
To determine the prevalence of pathologic changes in the endometrium of tamoxifen-treated asymptomatic postmenopausal patients with breast cancer. Subjects and Fifty postmenopausal asymptomatic breast cancer patients with positive estrogen receptor status were treated with 20 mg of tamoxifen daily for a period of 5-60 months. The control group consisted of 30 asymptomatic postmenopausal breast cancer patients who were negative for estrogen receptor and therefore did not receive tamoxifen. Endometrial biopsies were performed using Pipelle endometrial suction curette at least 5 months after the study began. The endometrium was classified as atrophic [negative finding] and proliferative or hyperplastic [positive findings]. The study and control groups were compared for demographic characteristics, risk factors for endometrial cancer, histological findings and the duration of tamoxifen treatment. A significantly greater prevalence of endometrial abnormalities existed among the tamoxifen-treated than control patients [76 vs. 33%, p < 0.001]. The abnormal endometrial changes were further demarcated in both groups into proliferative [54 vs. 26.7%, p = 0.02] and hyperplastic [22 vs. 6.6%, p = NS]. In the study group, 63.6% of hyperplastic endometrium was simple hyperplasia and 36.4% was complex/no atypia hyperplasia, while in the control group all the cases were simple hyperplasia. No endometrial cancer was detected in either group. In addition, there was a positive association between the duration of tamoxifen exposure [<1 year vs. >/= 1 year] and the endometrial abnormalities [46.6 vs. 88.6%, p = 0.003; proliferative 57.1 vs. 74.1%, p = 0.015; hyperplastic 42.8 vs. 25.8%, p = NS]. The adjuvant use of tamoxifen is associated with significant time-dependent abnormal endometrial changes among patients with cancer of the breast