[A Case of Primary Small Cell Carcinoma in the Breast with Neoadjuvant Chemotherapy That Were Difficult to Select Chemotherapy].

Primary small cell carcinoma in the breast is a rare and aggressive tumor, and a standard treatment strategy has not been established. Herein, we report a 35-year-old woman with primary small cell carcinoma in the breast. She had an 8 cm diameter tumor in the right breast. She was diagnosed with small cell carcinoma(cT3N1M0, cStage ⅢA)in the right breast, and neoadjuvant chemotherapy was planned. She received a combination chemotherapy of cisplatin(CDDP)and etoposide(VP- 16)based on the regimen for pulmonary small cell carcinoma; however, the disease showed progression. Therefore, 5-FU plus epirubicin plus cyclophosphamide(FEC)and weekly paclitaxel(PTX)chemotherapy based on a regimen for breast cancer were administered, and the tumor was partially reduced in size. Modified radical mastectomy followed by radiotherapy and hormonal therapy was performed. Ten months after the surgery, multiple liver and bone metastases occurred, and the patient died the following month. Further studies in other such patients are needed.