Prognostic factors in metaplastic carcinoma of the breast: a multi-institutional study

Abstract

Background:Metaplastic breast carcinoma (MBC) is a rare type of breast cancer that has basal-like characteristics and is perceived to have poorer prognosis when compared with conventional no specific type/ductal carcinomas (ductal/NST). However, current data on MBC are largely derived from small case series or population-based reports. This study aimed to assess the clinicopathological features and outcome of MBC identified through an international multicentre collaboration.Methods:A large international multicentre series of MBC (no=405) with histological confirmation and follow-up information has been included in this study. The prognostic value of different variables and outcome has been assessed and compared with grade, nodal status and ER/HER2 receptor-matched ductal/NST breast carcinoma.Results:The outcome of MBC diagnosed in Asian countries was more favourable than those in Western countries. The outcome of MBC is not different from matched ductal/NST carcinoma but the performance of the established prognostic variables in MBC is different. Lymph node stage, lymphovascular invasion and histologic subtype are associated with outcome but tumour size and grade are not. Chemotherapy was associated with longer survival, although this effect was limited to early-stage disease. In this study no association between radiotherapy and outcome was identified. Multivariate analysis of MBC shows that histologic subtype is an independent prognostic feature.Conclusions:This study suggests that MBC is a heterogeneous disease. Although the outcome of MBC is not different to matched conventional ductal/NST breast carcinoma, its behaviour is dependent on the particular subtype with spindle cell carcinoma in particular has an aggressive biological behaviour. Management of patients with MBC should be based on validated prognostic variables.

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

“…However, this finding should be interpreted with caution as the group is not uniform in terms of other clinical and pathological confounders. These findings are in part similar to the findings reported by Rakha et al (13) who found that MBC with mesenchymal differentiation and SCC had better outcome than spindle and mixed spindle and SCC.…”

“…Some studies did not record the histologic subtypes (10,15). While some studies (4,9,11,12) showed a significant survival difference, others (8,10,13,15) concluded that while MBC tumors have poor prognostic indicators at presentation, they behave similarly to matched controls.…”

“…There was inconsistency in data handling and analysis. While some authors performed matching (4,8–13,15), some did not match instead they compared with either all TNBC (14) or with BC regardless of tumor molecular subtype (5). There was also inconsistency in the chosen variables for matching, ranging from only one variable such as Nottingham grade (4), or stage (12), to a more comprehensive matching including age, stage, and therapy modality (11 and current study).…”

“…Rakha et al (13) analyzed 405 cases of MBC and compared them to IC-NST (285 cases) matched in terms of age, grade, lymph node stage, ER and HER2 status. Treatment modality was not matched.…”

“…These frequencies vary in different studies. The largest study by Rakha et al (13) found that the most common subtype in the western world was spindle cell carcinoma (34%) while SCC was the most common in the eastern world (34%). Luini et al (9) found that MBC with mesenchymal differentiation was the most common in European patients.…”