A case of metaplastic breast cancer that showed a good response to platinum-based preoperative chemotherapy

Patients with metaplastic breast cancer (MBC) exhibit reduced response to chemotherapy and have poor prognosis. We investigated a case of MBC that showed a positive response to preoperative chemotherapy, resulting in near pathological complete response (pCR). A 59-year-old woman complained of a lump in her right breast. Magnetic resonance imaging (MRI) showed the presence of a solid mass that was 24 mm in diameter. The pathological diagnosis was MBC with cartilaginous differentiation. The clinical stage was T2N0M0, stage IIA according to the International Union against Cancer (UICC) criteria. To observe the response to chemotherapy, we gave her preoperative chemotherapy. The patient was monitored closely, since we realized that failure of chemotherapy carries a risk of tumor progression. Evaluation was carried out using ultrasound, MRI, fluorodeoxyglucose (FDG) positron emission tomography (PET), and a Ki-67 labeling index after the first cycle of chemotherapy, and ultrasound after each additional cycle. FDG-PET showed a positive response after the first cycle of chemotherapy. The patient underwent 4 cycles of docetaxel (75 mg/m²) and cisplatin (75 mg/m²) followed by 4 cycles of cyclophosphamide (500 mg/m²), doxorubicin (50 mg/m²), and cisplatin (50 mg/m²). Ultrasound showed decreases in tumor size after each cycle of chemotherapy. After chemotherapy, MRI showed nearly complete regression of the tumor. Partial mastectomy was performed. Pathological examination showed few cancer cells remaining, indicating near pCR. We report a case of MBC that responded well to platinum-based preoperative chemotherapy. We propose that preoperative chemotherapy may be an option for treatment of MBC in conjunction with careful monitoring.