A clinicopathologic analysis of 45 patients with metaplastic breast carcinoma

Objectives: Metaplastic breast carcinomas (MBCs) are rare, aggressive cancers lacking targeted therapy. Here, we review the clinicopathologic features, treatment, and outcomes of patients with MBC treated at our institution. Methods: We searched clinical and pathology databases for patients with histologically confirmed MBC from 1999 to 2012. We estimated survival probabilities using the Kaplan-Meier method and evaluated prognostic factors using Cox regression. Results: Forty-five cases were identified, including chondroid (24%), spindled (20%), sarcomatoid (16%), squamous (11%), and mixed (29%) histologic subtypes. Median tumor size was 3 cm, with 86% grade III and 69% triple-negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. Most had negative lymph nodes, and two patients had metastases at diagnosis. Six patients received neoadjuvant therapy, with one pathologic complete response. All patients underwent surgery, 60% received adjuvant radiation, and 58% had adjuvant chemotherapy. Five-year recurrence-free survival was 64%; 5-year overall survival was 69%. Tumor size, history of breast cancer, and mixed histology were associated with inferior outcomes. Conclusions: We report one of the largest single-institution series of patients with MBC. MBC is associated with a poor prognosis, despite low nodal involvement. Most patients in this series had high-grade, triple-negative tumors and were treated with optimal therapy.