Metaplastic Carcinoma of the Breast Is More Aggressive Than Triple-negative Breast Cancer: A Study From a Single Institution and Review of Literature.

BACKGROUND

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.

MATERIALS AND METHODS

We reviewed MBC cases (n = 46) from our institution. The following variables were recorded: tumor histologic subtype, Nottingham grade, tumor size, lymph node status, Tumor, Node, Metastases 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 were extracted from the breast cancer database. To compare the survival between MBC and TNBC, a subgroup of MBC cases (n = 40) were matched with TNBC cases (n = 40) on the basis of known prognostic confounders.

RESULTS

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 = .014) and was more likely to recur (34% vs. 15.5%; P = .004). More MBC patients died from disease than TNBC (29% vs. 16%; P = .05). In the multivariate analysis, MBC had approximately twice the risk of local recurrence than TNBC (95% confidence interval, 1.01-3.83; P = .05). MBC patients had worse DFS and OS than the matched TNBC patients (P < .001 and P = .033, respectively). A review of the literature comparing MBC versus TNBC is presented.

CONCLUSION

Our results suggest that MBC is clinically more aggressive than TNBC. Further studies might help delineate the differences between these 2 entities.