Study objective: To evaluate the estrogenic effects of tamoxifen on the endometrium in postmenopausal women with breast cancer.
Design: Consecutive study (Canadian Task Force classification II-2).
Setting: University-affiliated hospital.
Patients: Thirty-three women. Interventions. All patients underwent transvaginal sonography (TVS) and color flow Doppler of endometrial vessels, hysteroscopy, and, if necessary, endometrial biopsy or other operative hysteroscopic procedures.
Measurements and main results: In four women the endometrium was thin on TVS and atrophic at hysteroscopic assessment. In 29 women with thick endometrium on TVS, hysteroscopy and endometrial biopsy showed atrophy (11 patients), hyperplasia (5), polyps (11), and well-differentiated adenocarcinoma (2). The two endometrial cancers were present in women with uterine bleeding. In women with positive histologic findings, the endometrium was significantly thicker (p = 0.04) and duration of tamoxifen therapy longer than in those with negative findings, although this was not statistically significant (p = 0.067).
Conclusion: We believe regular assessment of the endometrium by TVS should be performed in postmenopausal patients at the start of the tamoxifen therapy, and hysteroscopy in women with a thick endometrium or postmenopausal bleeding. We believe that patients with thin endometrium on TVS at the beginning of tamoxifen therapy, who have no abnormal uterine bleeding should be screened with these examinations for 2 years.