Prospective Exploratory Study of the Effects of Postoperative Endocrine Medication on the Endometrium in Breast Cancer Patients.

Objective: This study aimed to investigate the pathological effects of long-term postoperative endocrine medication on the endometrium in breast cancer patients. Methods: Data of 99 patients with primary breast cancer who underwent hysteroscopy and obtained endometrial biopsy from 1 June 2018 to 31 December 2021 at the Beijing Obstetrics and Gynecology Hospital, Capital Medical University. Beijing Maternal and Child Health Care Hospital were prospectively collected. Results: Hysteroscopy was performed followed by endometrial histopathological examination in 99 breast cancer patients, including 44 taking tamoxifen (TAM), 26 taking other endocrine drugs, and 29 not taking endocrine drugs. The endometrial thickness in the TAM group was significantly higher than that in the other endocrine drug groups and the group not taking endocrine drugs (p=0.017). The receiver operating characteristic curves for the abnormal premenopausal endometrial thickening were plotted in this study; an endometrial thickness of 15.5 mm seen on ultrasound could be used as the most accurate ultrasound diagnostic threshold for the diagnosis of abnormal premenopausal endometrial hyperplasia, with an area under the curve of 0.888 (95% CI: 0.716, 1.000), a sensitivity of 100%, and a specificity of 75%, which was consistent with the results of our previous retrospective study. An endometrial thickness of ≥5 mm in postmenopausal women with breast cancer taking TAM was still used as the cut-off value for routine ultrasound diagnosis of abnormal postmenopausal endometrial hyperplasia. Conclusion: An ultrasound endometrial thickness (proliferative phase) of >15 mm in premenopausal patients can be used as the most accurate ultrasound diagnostic threshold for the diagnosis of abnormal endometrial hyperplasia. After menopause, an ultrasound endometrial thickness of ≥5 mm is still used as the criterion for diagnosing abnormal endometrial hyperplasia. Older patients should be monitored for signs of vaginal bleeding and fluid discharge, and hysteroscopy should be performed if necessary to ascertain the endometrial condition.