Metaplastic sarcomatoid carcinoma of the breast appears more aggressive than other triple receptor-negative breast cancers

Abstract

Metaplastic sarcomatoid carcinoma (MSC) of the breast is usually triple receptor (ER, PR, and HER2) negative and is not currently recognized as being more aggressive than other triple receptor-negative breast cancers. We reviewed archival tissue sections from surgical resection specimens of 47 patients with MSC of the breast and evaluated the association between various clinicopathologic features and patient survival. We also evaluated the clinical outcome of MSC patients compared to a control group of patients with triple receptor-negative invasive breast carcinoma matched for patient age, clinical stage, tumor grade, treatment with chemotherapy, and treatment with radiation therapy. Factors independently associated with decreased disease-free survival among patients with stage I-III MSC of the breast were patient age > 50 years (P = 0.029) and the presence of nodal macrometastases (P = 0.003). In early-stage (stage I-II) MSC, decreased disease-free survival was observed for patients with a sarcomatoid component comprising ≥ 95% of the tumor (P = 0.032), but tumor size was the only independent adverse prognostic factor in early-stage patients (P = 0.043). Compared to a control group of triple receptor-negative patients, patients with stage I-III MSC had decreased disease-free survival (two-sided log rank, P = 0.018). Five-year disease-free survival was 44 ± 8% versus 74 ± 7% for patients with MSC versus triple receptor-negative breast cancer, respectively. We conclude that MSC of the breast appears more aggressive than other triple receptor-negative breast cancers.

Fig. 1

Representative cases of metaplastic sarcomatoid carcinoma with varying amounts of carcinomatous and sarcomatous components (a–c) or pure sarcomatoid morphology (d)

Fig. 2

Disease-free survival for stage I–III MSC patients according to patient age (a), tumor size (b), and lymph node status (c)

Fig. 3

Disease-free survival for early-stage (stage I–II) MSC patients according to proportion of sarcomatoid component (a) and tumor size (b)

Fig. 4

Disease-free survival for stage I–III MSC patients versus triple-negative breast cancer patients (a) and for early-stage (stage I–II) MSC patients versus triple-negative breast cancer patients (b). Disease-free survival for stage I–III MSC patients diagnosed and treated after 1996 versus triple-negative patients (c), and overall survival for stage I–III MSC patients diagnosed and treated after 1996 versus triple-negative patients (d)