Clinicopathologic Features and Outcomes of Metaplastic Breast Carcinoma: Comparison with Invasive Ductal Carcinoma of the Breast

PURPOSE: Metaplastic breast carcinoma (MBC) is rare. Its clinicopathologic features and prognosis are uncertain. The aim of this study was to evaluate the clinicopathologic characteristics and outcomes in comparison with invasive ductal carcinoma (IDC). MATERIALS AND METHODS: We reviewed the data of 29 patients with MBC and 4,851 patients with IDC, who received surgery at Yonsei University Severance Hospital between 1980 and 2008. Various clinicopathologic features, recurrence free, and overall survival were investigated and compared to each other. RESULTS: Stage IV cases at diagnosis were more common in MBC (10.3%) than in IDC (0.9%). The incidence rates of triple negative breast cancer (TNBC) were significantly higher in MBC (84.0%) than in IDC (20.1%). Larger tumors (>2 cm) and lower tendency of axillary metastasis were frequently observed in MBC. Only one of 24 preoperative core needle biopsies (CNB) correctly diagnosed MBC. There was no significant difference in survival between the two groups. CONCLUSION: MBC was characterized by a higher incidence of TNBC, larger tumor size, and lower tendency of axillary metastasis, and was difficult to diagnose with CNB. Although the incidence of stage IV disease at diagnosis was higher in MBC, the survival rates of stage I-III were comparable to those of IDC.