Outcomes of metaplastic breast cancer versus triple negative breast cancer: a propensity score matching analysis

Abstract

Abstract Purpose This study aims to compare the survival outcomes of MBC with triple-negative breast cancer (TNBC) and identify prognostic factors that influence MBC survival. Methods Patients with non-metastatic MBC or TNBC were reviewed from our database from 2002 to 2021. Patient clinicopathologic features and treatment were analyzed with respect to outcomes including disease progression-free survival (DFS), and overall survival (OS). Propensity score matching (PSM) with a one-to-three matching between MBC and TNBC was performed. Results A total number of 857 female patients (76 MBC and 781 TNBC) were included in this study, with median age in 49 years (28–77 years). A subgroup of triple negative MBC (n = 60) was matched with TNBC (n = 180) cases based on patient characteristics and treatment. OS and DFS were significantly worse in the MBC group before (p = 0.0046 both) and after (p = 0.011 and p = 0.0046, respectively) PSM. Multivariable analysis revealed larger tumor size (T > 5cm) (HR = 3.797, 95%CI 1.118–12.902, p = 0.032) and lymph nodal status (N3 vs N0-2, HR = 6.149 95%CI 1.499–25.229, p = 0.012) were associated with worse OS after PSM. Among the 76 MBC patients, higher T stage and mesenchymal differentiation were associated with worse overall survival (pT1/2 vs pT3/4 and mesenchymal differentiation vs other type, p = 0.007 and p = 0.011, respectively). Lymph node positive and mesenchymal differentiation were associated with worse disease-free survival (Figs. 5 and 6, p = 0.005 and p < 0.001, respectively). Conclusions Compared with TNBC, MBC tends to have a worse OS. Mesenchymal differentiation has a worse DFS than other subtypes of MBC.