The effect of tamoxifen therapy on the endometrium and ovarian cyst formation in patients with breast cancer

To evaluate the effect of tamoxifen on female reproductive organs in women with breast cancer. We retrospectively reviewed the medical records of 309 women with breast cancer who were currently receiving tamoxifen and undergoing regular gynecological examination. We evaluated 92 pre- and 217 postmenopausal women. The prevalence of endometrial thickening was 12% in the pre- and 10.6% in the postmenopausal group. An endometrial biopsy was performed in 43 women and confirmed endometrial cancer in 1, endometrial polyps in 14, and endometrial hyperplasia in 4 women. Transvaginal ultrasonography showed 25 cases of newly developed ovarian cysts. Most ovarian cysts had disappeared during follow-up. Tamoxifen use in women with breast cancer causes few complications and is considered safe for female reproductive organs in case of regular gynecological examination.