BACKGROUND AND OBJECTIVE:  Uterine carcinosarcoma, also known as malignant mixed Mullerian tumor, is a rare uterine malignancy. Although the origin and prognosis of this cancer remain undetermined, the Mullerian ducts are believed to be the main origin. This tumor has the ability to change into epithelial and mesenchymal components and is more common among black and postmenopausal women. Prior history of radiation therapy and use of tamoxifen also contribute to this condition. The clinical characteristics of uterine carcinosarcoma, including postmenopausal bleeding, are similar to those of endometrial cancer. This condition with a poor prognosis and aggressive nature may be overcome by a combination of therapies including surgery, chemotherapy, and radiotherapy. Herein, we present a case of uterine carcinosarcoma associated with tamoxifen use in a menopausal patient.

CASE REPORT: The patient was a 67-year-old menopausal woman (G9, P5, L5, Ab4), who underwent lumpectomy and chemoradiotherapy ten years ago due to estrogen receptor-positive breast cancer (ductal carcinoma). The patient received 40 mg of tamoxifen on a daily basis, and after six years of tamoxifen use, she experienced postmenopausal bleeding. Increased endometrial thickness appeared in the ultrasound, and uterine carcinosarcoma was diagnosed, based on pathologic evaluations. The patient received multi-modal therapy, and after a year of follow-up, no specific problems were reported.

CONCLUSION: According to the results, symptoms of uterine cancer should be taken into account in menopausal patients consuming tamoxifen.