Background
Metaplastic breast carcinoma (MBC) is a rare subtype of breast carcinoma less responsive to conventional chemotherapy relative to usual breast carcinomas such as ductal and lobular subtype. In molecular terms, MBC usually clusters with triple negative breast cancers (TNBC), but MBCs portray a worse prognosis in comparison with TNBC. Published studies investigating MBCs for specific biomarkers of therapy response are rare and limited by the methodological approaches.