A Case of Androgen Receptor-positive Triple Negative Breast Cancer with Good Response to Anti-androgen Therapy

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Anti-androgen therapy has been proposed to be effective in the treatment of androgen receptor (AR)-positive triple negative breast cancer (TNBC). Herein, we report on the case of a 91-year-old female patient with AR-positive TNBC who underwent anti-androgen therapy and had a good response. Because of dementia, the patient lives in an aged care facility. It was here that a staff member noticed a mass with a rash on the patient's breast. Consequently, the patient was sent for further examination. Ultrasonography revealed an irregularly shaped, indistinct hypoechoic mass measuring 19×18×9mm located in the upper outer quadrant of the left breast. Core needle biopsy (CNB) was performed and the mass was diagnosed as apocrine carcinoma. Further immunohistochemical analysis showed that the mass was AR-positive TNBC. Anti-androgen therapy was determined to be the optimal treatment option for this patient. The Institutional Review Board approval the off-label use of an anti-androgen for the treatment of this patient, who was subsequently treated with the anti-androgen flutamide. After 8 months, the size of the tumor had reduced to 15×9×5mm.