Metaplastic breast carcinomas are basal-like tumours.
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.
Reis-Filho
J S
JS
The Breakthrough Toby Robins Breast Cancer Research Centre, Institute of Cancer Research, London, UK. jorgerf@icr.ac.uk
Milanezi
F
F
Steele
D
D
Savage
K
K
Simpson
P T
PT
Nesland
J M
JM
Pereira
E M
EM
Lakhani
S R
SR
Schmitt
F C
FC
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
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