Ultrasonographic measurement of endometrial changes following discontinuation of tamoxifen treatment in postmenopausal breast cancer patients

Objective To assess whether there is a decrease in endometrial thickness following discontinuation of tamoxifen treatment as measured by ultrasound. Design Prospective study. Setting Department of Obstetrics and Gynaecology, Sapir Medical Centre, Kfar-Saba, Israel. Population Fifty-eight postmenopausal women with breast cancer who were treated with tamoxifen. Methods Transvaginal ultrasonographic measurements of endometrial thickness. Main outcome measures Evaluation of the changes of endometrial thickness and the frequency the endometrium reached a thickness of less than or equal to 5 mm at different time intervals after stopping tamoxifen treatment. Results There was a significant decrease in median thickness of the endometrium, within six months after stopping tamoxifen, from 7.75 mm measured at the last ultrasonographic study performed before tamoxifen discontinuation down to 5.2 mm (P = 0.002). There were no further reductions in endometrial thickness, and it remained constantly low in subsequent ultrasonographic studies which were performed at various times up to 30 months following the discontinuation of tamoxifen treatment. While taking tamoxifen, only 25.9% of the women had an endometrial thickness of less than or equal to 5 mm, This proportion doubled in their first six months after stopping. Conclusions Median thickness of endometrial thickness significantly reduced within six months following tamoxifen discontinuation, and remained constantly low thereafter. This finding may support use of ultrasonographic imaging for the measurement of tamoxifen's effect on the endometrium of postmenopausal breast cancer patients.