Changes mimicking endometrial neoplasia in postmenopausal, tamoxifen‐treated women with breast cancer: a transvaginal Doppler study

In menopausal patients with breast cancer who receive tamoxifen therapy, transvaginal sonography may show an abnormal endometrium. Our objective was to evaluate the effects of prolonged tamoxifen therapy on endometrial blood flow in postmenopausal patients with breast cancer, and to correlate blood flow characteristics with the sonographic appearance of the endometrium and its pathology. Transvaginal color Doppler ultrasound examinations were performed on 45 postmenopausal women (age range 54–70 years) with breast cancer, who had been treated with tamoxifen for 1–3 years. Twenty women (Group 1) had a thick, irregular, cystic endometrium of ≥ 5 mm, and 25 (Group 2) showed a thin endometrium of < 5 mm. The blood flow response was assessed by visualization of arterial waveforms in the endometrial and subendometrial regions with a transvaginal color flow imaging system. Resistance indexes (RI) were calculated for analysis and correlated with endometrial appearance and histology. The mean RI in Group 1 was 0.39 ± 0.10 (range 0.32–0.54), while the mean RI in Group 2 was 0.79 ± 0.10 (range 0.54–0.90; p < 0.001). On histology, 12 patients in Group 1 showed atrophic endometria confirmed by hysteroscopy, while in the remaining eight, endometrial polyps were found. In Group 2, all patients had scanty, atrophic endometria. Six of the eight patients with endometrial polyps had an RI of < 0.4 and none had malignant changes. These data suggest that tamoxifen therapy in women with postmenopausal breast cancer induces endometrial, morphological and blood flow changes, mimicking endometrial neoplasia. If low RI (0.4) and an abnormal appearance of the endometrium had been relied on as criteria that indicate malignancy, six of our patients (30%) with thick endometria would have been misdiagnosed as having carcinoma.