Investigation of endometrial abnormalities in asymptomatic women treated with tamoxifen and an evaluation of the role of endometrial screening

Purpose: Tamoxifen is the most commonly prescribed adjuvant therapy for wom en with breast cancer. It has agonist activity on the endometrium and is as sociated with an increased risk of endometrial cancer. The aim of this stud y was to evaluate whether screening with transvaginal ultrasound (TV USS) w ith or without hysteroscopy is worthwhile. Patients and Methods: A total of 487 women with breast cancer, 357 treated with tamoxifen and 130 controls, were screened with TV USS, and endometrial thickness was measured. Women with thickened endometrium underwent outpati ent hysteroscopy. Results: Length of time on tamoxifen ranged from 5 to 191 months (mean, 66 months), and endometrial thickness ranged from 1 to 38 mm (mean, 7.3 mm), W omen treated with tamoxifen had significantly thicker endometrium than did controls (P < .0001). There was a statistically significant (P < .0001) pos itive correlation between length of time on tamoxifen and endometrial thick ness. One hundred forty-five women had endometrium greater than 5 mm on USS , and 134 underwent successful outpatient hysteroscopy, 61 of whom had atro phic endometrium, resulting in a 46% false-positive scan rate. The remainin g women all had benign features to explain the USS findings. Conclusion: TV USS detects a high incidence (41%) of apparent endometrial t hickening in women treated with tamoxifen, although 46% had atrophic endome trium on further assessment, and none of the remaining asymptomatic women h ad significant lesions. Length of time on tamoxifen relates to endometrial thickening as measured by TV USS. TV USS is a poor screening tool because o f the high false-positive rate. The low frequency of significant findings s uggests that endometrial screening in asymptomatic women is not worthwhile, (C) 1999 by American Society of Clinical Oncology.