Background: Breast cancer is most common malignancy in women. The subtype of breast cancer are classified into luminal type, HER2 type, Triple negative type. About 70% of the breast cancer patient are luminal type. Endocrine treatment is an important for luminal breast cancer. Several medicines have been used, including aromatase inhibitor, gonadotropin-releasing hormone(GnRH) agonists, selective estrogen receptor modulator(SERM), selective estrogen receptor down regulator(SERD). Among these, tamoxifen is still a commonly used drug, but there are some well-known side effects. There are many problems, but the well-known side effects are hot flush, cardiovascular complication, sexual problem, cataracts, thromboembolism. In addition, life-threatning endometrial cancer can also occur.
Case report: A 47-year-old female patient underwent surgery for breast cancer in 2014. Chemotherapy and radiotherapy were used as adjuvant treatment. Hormone therapy with tamoxifen was started in August 2014. The patient was admitted to our hospital with no recurrence or metastasis. Endometrial polyp on gynecologic ultrasonography in March 2017. The patient was scheduled for an examination 6months later, but she was diagnosed as an atypical mass on ultrasonography because she had an unusual hemorrhage. Histological examination revealed endometrial cancer. And then, total abdominal hysterectomy and pelvic lymph node dissection were performed. Chemotherapy and radiotherapy were performed for endometrial cancer.
Conclusion: Tamoxifen is one of the good drugs used to prevent the recurrence of breast cancer, but various side effects have been reported, and some side effects, such as endometrial cancer, are threatening survival. Therefore, the patient should be careful about the gynecological history, it is advisable to have a gynecologic examination, annually