ENDOMETRIAL CHANGES IN POSTMENOPAUSAL BREAST-CANCER PATIENTS RECEIVING TAMOXIFEN

Objective: To assess the estrogenic effect of tamoxifen and associated pathologic changes of the endometrium in postmenopausal breast cancer patients. Methods: The endometrium of 103 gynecologically asymptomatic postmenopausal breast cancer patients was examined. Fifty-one had been treated with tamoxifen and 52 had not received any hormonal treatment. The two groups were similar in age, parity, age at menopause, and body mass index. Results: Compared with the control subjects, the tamoxifen patients had a thicker endometrium (mean +/- standard deviation 10.4 +/- 5.0 versus 4.2 +/- 2.7 mm; P = .0001) and larger uterine volume (45 +/- 27 versus 25 +/- 11 cm3; p =.001), as determined by transvaginal sonography. Hysteroscopy showed an atrophic endometrium in 28% of the patients in the tamoxifen group, as compared with 87% of the control patients (P = .0001). Endometrial polyps were more frequent in the tamoxifen group (36 versus 10%; P = .004), which included one patient with atypical hyperplasia, one with adenomatous hyperplasia, and one with endometrial adenocarcinoma; two controls had endometrial adenocarcinoma. Conclusion: The results provide evidence for an estrogenic effect of long-term tamoxifen treatment on the postmenopausal uterus and show it to be associated with an increased occurrence of polyps.