Prognosis of Metaplastic Breast Cancer: Poorer Than the Rest of Triple-Negative Breast Cancer.

Abstract

Abstract Background: The biologic behavior of metaplastic breast cancer (MBC) has not been well elucidated due to its rarity and heterogeneity. This study was designed to assess the clinical and tumor characteristics and outcomes of MBC patients as compared with invasive ductal carcinoma (IDC) in general and the triple-negative (TN) subtype.Materials and methods: This study included 35 MBC and 2,839 IDC patients diagnosed at the National Cancer Center, Korea between 2000 and 2008. We, retrospectively, reviewed the clinicopathologic characteristics and clinical outcomes.Results: The mean age was 47.4 years for MBC group and 48.3 years for IDC group. The MBC group presented with larger tumors (≥ T2, 78.8% vs 41.0%; P<0.001), higher histologic grade (grade 3, 92.0% vs 44.6%; P<0.001), fewer ER and PgR positivity (ER+, 14.3% vs 69.0% ; P<0.001 and PgR+, 25.7% vs 66.1%; P<0.001), higher Ki-67 expression (35.5%±26.2% vs 20.6% ±19.8%; P=0.024) and more TN subtypes (48.6% vs 11.9%; P<0.001) than IDC group. Excluding de novo stage IV patients, 14 of 32 (43.7%) MBC patients and 260 of 2782 (9.4%) IDC patents developed disease recurrence with a median follow-up of 36.2 months (range, 4.9-117.8 months). MBC was a poor prognostic factor for disease recurrence in univariate and multivariate analysis (HR 5.19; 95% CI, 2.04-13.18; P=0.001). MBC patients demonstrated aggressive pathologic features and experienced more disease recurrence (HR 4.77; 95% CI, 1.99-11.44; P=0.001) even when compared with 330 patients with TN subtype.Conclusions:Patients with metaplastic breast carcinoma appeared to have inherent aggressive tumor biology with poorer clinical outcomes than those with IDC in general and TN subtype.Partly supported by NCC Grant No 0610240 Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4057.