[A case of estrogen receptor-positive metastatic breast cancer in a postmenopausal woman treated with ethinyl estradiol].

The patient was 77-year-old woman whose breast cancer had metastasized to the bone and soft tissue 5 years after surgery. Although she had been sequentially treated with endocrine therapies following chemotherapies, new metastatic lesions in the pleura and skin appeared 8 years after recurrence. The biopsied skin tissue showed high positivity for estrogen receptor(ER), was negative for human epidermal growth factor receptor 2(HER2), and had a low Ki-67 labeling index. Following the treatment with exemestane(EXE)for 3 months, ethinyl estradiol(EE2)was administered at 3mg/day. After 4 months of treatment, the lymph nodes shrunk to 35% of their size and pleural effusion disappeared. The efficacy of EE2 was observed for 10 months. Subsequently, fulvestrant was administered because the skin lesions showed progressive disease. Adverse events such as nausea and general fatigue were observed at the beginning of EE2 therapy. Pigmentation of the nipple and areola and cystic swelling of the cervical canal were observed after a few months. This therapy can be considered to be effective in patients with ER-positive metastatic breast cancer who have been heavily treated with endocrine therapies and chemotherapies.