Breast cancer has become the most common malignant tumor threatening the health of Chinese women in recent years. The use of tamoxifen (TAM) has successfully reduced the recurrence and progression of estrogen receptor-positive breast cancer, however, it also increases the risk of endometrial lesions.

To explore the risk factors for endometrial lesions in breast cancer patients taking TAM, determine the optimal threshold value of endometrial thickness, and improve the positive detection rate of hysteroscopy.

Breast cancer patients taking TAM (20 mg/d) who underwent hysteroscopic endometrial biopsy admitted to the Department of Gynecology of the First Affiliated Hospital with Nanjing Medical University from January 2015 to January 2022 were retrospectively selected as the study objects and divided into the negative hysteroscopic endometrial biopsy group (normal endometrium) and positive hysteroscopic endometrial biopsy group (endometrial lesions including endometrial polyps, endometrial hyperplasia without atypia, endometrial atypical hyperplasia and endometrial carcinoma). Clinical data of the patients were collected, including age, BMI, history of hypertension and diabetes, delivery times, presence of menopause and abnormal uterine bleeding/postmenopausal bleeding (AUB/PMB), receiving of chemotherapy, duration of TAM treatment, use of gonadotropin-releasing hormone agonists (GnRH-a), endometrial thickness, echo features of intrauterine lesions. Multivariate Logistic regression analysis was used to explore the risk factors for endometrial lesions in breast cancer patients taking TAM. The receiver operating characteristic (ROC) curve of endometrial thickness for predicting endometrial lesions detected by hysteroscopy was plotted, and the area under the ROC curve (AUC) and its 95%CI were calculated to determine the optimal cut-off value of endometrial thickness for receiving hysteroscopic surgery.

The proportion of patients with AUB/PMB, duration of TAM treatment≥24 months, intrauterine hyperechoic lesions and endometrial thickness in the positive hysteroscopic endometrial biopsy group were higher than those in the negative hysteroscopic endometrial biopsy group (P<0.05). Multivariate Logistic regression analysis showed that AUB/PMB〔OR=7.731, 95%CI (1.949, 30.699), P=0.004〕, endometrial thickening〔OR=1.223, 95%CI (1.091, 1.371), P=0.001〕 and intrauterine hyperechoic lesions〔OR=13.383, 95%CI (2.751, 65.103), P=0.001〕were independent risk factors for endometrial lesions detected by hysteroscopy in breast cancer patients taking TAM. The AUC of endometrial thickness for predicting endometrial lesions detected by hysteroscopy in breast cancer patients taking TAM was 0.753〔95%CI (0.638, 0.868), P<0.001〕, with the Youden index of 0.54, optimal cut-off value of 9.15 mm, sensitivity and specificity of 0.755 and 0.786, respectively.

The risk of endometrial lesions is increased in breast cancer patients taking TAM with AUB/PMB, endometrial thickness≥9.15 mm suggested by ultrasound and intrauterine hyperechoic lesions, when the hysteroscopy and endometrial biopsy should be actively considered.

近年来乳腺癌已成为威胁中国女性健康的第一大恶性肿瘤，他莫昔芬（TAM）的使用成功地减少了雌激素受体阳性乳腺癌的复发和进展，但同时也增加子宫内膜病变的风险。

探索服用TAM的乳腺癌患者子宫内膜病变的高危因素，确定子宫内膜厚度预测该类患者子宫内膜病变的最佳界值，提高宫腔镜手术的阳性检出率。

回顾性选取2015年1月—2022年1月南京医科大学第一附属医院妇科收治的接受宫腔镜下内膜活检的服用TAM（20 mg/d）的乳腺癌患者为研究对象。将患者分为宫腔镜内膜活检阴性组（正常子宫内膜）和宫腔镜内膜活检阳性组（即子宫内膜病变，包括子宫内膜息肉、子宫内膜增生不伴不典型、子宫内膜不典型增生及子宫内膜癌）。收集患者的临床资料，包括年龄、BMI、高血压史、糖尿病史、分娩次数、是否绝经、是否存在异常子宫出血/绝经后出血（AUB/PMB）、是否化疗、TAM用药时间、是否使用促性腺激素释放激素激动剂（GnRH-a）、子宫内膜厚度、宫腔占位回声特征。采用多因素Logistic回归分析探究服用TAM的乳腺癌患者子宫内膜病变的危险因素。绘制子宫内膜厚度预测宫腔镜检出子宫内膜病变的受试者工作特征（ROC）曲线，并计算ROC曲线下面积（AUC）及其95%CI，确定最佳截断值。

宫腔镜内膜活检阳性组患者AUB/PMB、TAM用药时间≥24个月、宫腔内高回声占位比例及子宫内膜厚度高于宫腔镜内膜活检阴性组（P<0.05）。多因素Logistic回归分析结果显示，AUB/PMB〔OR=7.731，95%CI（1.949，30.699），P=0.004〕、子宫内膜厚度增加〔OR=1.223，95%CI（1.091，1.371），P=0.001〕、宫腔内高回声占位〔OR=13.383，95%CI（2.751，65.103），P=0.001〕是服用TAM的乳腺癌患者宫腔镜检出子宫内膜病变的独立危险因素。子宫内膜厚度预测服用TAM的乳腺癌患者宫腔镜检出子宫内膜病变的AUC为0.753〔95%CI（0.638，0.868），P<0.001〕，约登指数为0.54，最佳截断值为9.15 mm，灵敏度为0.755，特异度为0.786。

当服用TAM的乳腺癌患者存在AUB/PMB、超声提示子宫内膜厚度≥9.15 mm、宫腔内存在高回声占位时发生子宫内膜病变的风险增高，应积极考虑宫腔镜检查及内膜活检。