ABSTRACT
Tamoxifen, which is often used in breast cancer therapy, has also been used in the treatment of patients with advanced and recurrent endometrial carcinoma. Tamoxifen has been shown to have significant benificial effects in the treatment of breast cancer patients as hormonal therapy. However, there is evidence that tamoxifen may affect other hormone sensitive organs, including the uterus and ovaries. An increased risk of endometrial polyps, endometrial hyperplasia and endometrial cancer has been reported in tamoxifen treated women. We are able to make this report because we have experienced uterine endometrial carcinosarcoma which is developed in a patient treated with tamoxifen for five years following a modified radical mastectomy due to breast cancer in our hospital.