Increased Risk of Endometrial Abnormalities in Breast Cancer Patients Taking Tamoxifen: The Need for Gynaecologic Surveillance

Objective: To evaluate the risk of abnormally thickened endometrium associated with tamoxifen treatment in ‍postmenopausal breast cancer patients. ‍
Methods: Two groups of asymptomatic postmenopausal breast cancer patients were recruited in the study. The ‍first consisted of 70 patients taking 20mg/day of tamoxifen for at least 6 months. The second group included 140 ‍patients without tamoxifen treatment. Endometrial evaluation using transvaginal ultrasonography (TVS) was ‍conducted for all patients. Fractional curettage was carried out for patients whose endometrial thickness was greater ‍than 5 mm on TVS. ‍
Results: The prevalence of abnormally thickened endometrium (greater than 5 mm on TVS) was significantly ‍higher in patients receiving tamoxifen (58.57% VS 10.71 %, P = 0.0001). Patients undergoing tamoxifen treatment ‍had a 5.61 relative risk of developing abnormally thickened endometrium (95% CI= 2.65 -11.86). ‍
Conclusion: Tamoxifen significantly increases the risk of developing abnormally thickened endometrium in ‍postmenopausal breast cancer patients. There is, thus, a true need for gynaecologic surveillance in such patients to ‍early detect neoplastic change of endometrium that may arise as a result of tamoxifen use.‍ ‍