Institutional Analysis of Metaplastic Breast Cancer

Triple-negative breast cancer (TNBC) is typically managed with neoadjuvant chemotherapy (NAC). Metaplastic breast cancer (MBC), a subtype of TNBC, demonstrates different histologic characteristics and less responsiveness to NAC. We performed this study to achieve a better understanding of MBC, including the impact of neoadjuvant chemotherapy. We identified patients diagnosed with MBC from January 2012 to July 1, 2022. A control group of TNBC breast cancer patients from 2020 who did not meet the criteria for MBC was identified. Demographic data, tumor and nodal characteristics, management strategies employed, response to systemic chemotherapy, and treatment outcomes were recorded and compared between groups. A total of 22 patients were included in the MBC group and demonstrated a 20% response to NAC compared to an 85% response rate in the 42 patients in the TNBC group (P = .003). Five patients have recurred (23%) in the MBC group compared to none in the TNBC group (P = .013).