We aimed to describe our experience with metaplastic breast carcinoma (MBC), evaluate its clinical outcome compared with triple negative breast cancer (TNBC), and provide a through and comprehensive review of the literature to date. We reviewed MBC cases (n=46) from our institution. The following variables were recorded, tumor histologic subtype, Nottingham grade, tumor size, lymph node status, TNM-stage, biomarkers profile, patient’s age and race, therapy modality (chemotherapy and radiation), and survival [disease free survival (DFS) and overall survival (OS)]. The clinical and pathological data for TNBC (n=508) cases was extracted from the BC database. In order to compare the survival between MBC and TNBC, a subgroup of MBC (n=40) were matched with TNBC (n=40) cases based on known prognostic confounders. There were 17 of 46 (37%) cases with mesenchymal differentiation, 12 (26.1%) squamous cell carcinoma, 14 (30.4%) spindle cell carcinoma, and 3 (6.5%) mixed type. MBC presented at a more advanced stage than TNBC (p=0.014) and was more likely to recur 34% vs. 15.5% (p= 0.004). More MBC patients died from disease than TNBC, 29% vs. 16% (p= 0.05). In the multivariate analysis, MBC had about twice the risk of local recurrence than TNBC (95% CI 1.01–3.83, p=0.05). MBC patients had worse DFS and OS than the matched TNBC patients (p <0.001 and p=0.033, respectively). A review of literature comparing MBC vs. TNBC is presented. Our results suggest that MBC is clinically more aggressive than TNBC. Further studies may help delineate the differences between these two entities.

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