title: Metaplastic breast carcinomas are basal-like tumours.
abstract: OBJECTIVE
  Recently, an immunohistochemical panel comprising antibodies against HER2, oestrogen receptor (ER), epidermal growth factor receptor (EGFR) and cytokeratin (CK) 5/6 was reported to identify basal-like breast carcinomas, as defined by cDNA microarrays. Our aim was to analyse a series of metaplastic breast carcinomas (MBCs) using this panel plus two other basal markers (CK14 and p63) and progesterone receptor (PR), to define how frequently MBCs show a basal-like immunophenotype.
  
  
  RESULTS
  Sixty-five cases were retrieved from the pathology archives of the authors' institutions and reviewed by three of the authors. Immunohistochemistry with antibodies for HER2, ER, EGFR, CK5/6, CK14 and p63 was performed according to standard methods. All but six cases (91%) showed the typical immunoprofile of basal-like tumours (ER- and HER2-, EGFR+ and/or CK5/6+). When CK14 and p63 were added to the panel, two additional cases could be classified as basal-like. The majority of MBCs lacked PR, except 4/19 (21%) carcinomas with squamous metaplasia.
  
  
  CONCLUSIONS
  Our results demonstrate that MBCs show a basal-like phenotype, regardless of the type of metaplastic elements. Moreover, as these neoplasms frequently overexpress EGFR (57%), patients with MBC may benefit from treatment with anti-EGFR drugs.
authors.affiliation: The Breakthrough Toby Robins Breast Cancer Research Centre, Institute of Cancer Research, London, UK. jorgerf@icr.ac.uk
authors.forename: J S
authors.initials: JS
authors.lastname: Reis-Filho
authors.forename: F
authors.initials: F
authors.lastname: Milanezi
authors.forename: D
authors.initials: D
authors.lastname: Steele
authors.forename: K
authors.initials: K
authors.lastname: Savage
authors.forename: P T
authors.initials: PT
authors.lastname: Simpson
authors.forename: J M
authors.initials: JM
authors.lastname: Nesland
authors.forename: E M
authors.initials: EM
authors.lastname: Pereira
authors.forename: S R
authors.initials: SR
authors.lastname: Lakhani
authors.forename: F C
authors.initials: FC
authors.lastname: Schmitt
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000145:classification / Q000378:metabolism / Q000473:pathology*; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007633:Keratins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D008679:Metaplasia; D018295:Neoplasms, Basal Cell / Q000145:classification / Q000378:metabolism / Q000473:pathology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D066246:ErbB Receptors; D007633:Keratins; D008565:Membrane Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C081876:CKAP4 protein, human