A Single-Center 18-Year Series of 73 Cases of Metaplastic Carcinoma of the Breast

Aim. To examine the clinical management of metaplastic breast cancer (MeBC), particularly the role of chemotherapy. Methods. This retrospective study included patients with MeBC (n = 73) from a tertiary breast cancer center: the “Centre des Maladies du Sein of the CHU de Québec–Université Laval.” The specimens were reviewed by two pathologists. Patient and tumor characteristics, systemic therapy (neoadjuvant and adjuvant), disease-free survival (DFS), and overall survival (OS) were recorded. Results. The median follow-up was 57.2 months. The mean tumor size was 39.5 ± 32.1 (range, 1–200) mm. Most were in grade 3 (75.3%), without evidence of clinical nodal involvement (75.3%), and triple-negative (79.5%). Chemotherapy was given to 49 (67.1%) patients. Thirty-seven patients (50.7%) underwent a mastectomy, and 22/37 (59.5%) received radiotherapy. Adjuvant chemotherapy was given to 36 patients (49.3%), and nine (12.3%) patients were treated with neoadjuvant chemotherapy. The 5-year OS and DFS rates were 60.2% and 66.8%. Among the nine patients who received neoadjuvant chemotherapy, three (33.3%) achieved a partial response, three (33.3%) had stable disease, and three (33.3%) had disease progression. The use of chemotherapy, especially in the adjuvant setting, had a significant positive effect on 5-year OS (P = 0.003) and 5-year DFS (P = 0.004). Nodal involvement was associated with worse OS (P = 0.049) but similar DFS (P = 0.157). Lumpectomy was associated with better 5-year OS (P < 0.0001) and DFS (P = 0.0002) compared with mastectomy. Conclusion. MeBC represents a rare heterogeneous group of malignancies with poor prognosis. Adjuvant chemotherapy was associated with improved OS and DFS. Patients should be carefully selected for neoadjuvant chemotherapy.