title: [Immunohistochemical characteristics of triple negative/basal-like breast cancer].
abstract: OBJECTIVE
  Triple-negative-breast-cancer that accounts for 10-20% of all breast carcinomas is defined by the lack of estrogen receptor, progesterone receptor, HER2 expression, and agressive clinical behavior. Triple-negative-breast-cancer is categorized into basal like and other types. The basal-like subtype is characterized by the expression of myoepithelial/basal markers.
  
  
  METHODS
  We studied 41 immunohistochemically triplenegative- breast-cancer patients to determine EGFR, Cytokeratine 5/6, p53, Ki67, GCDFP-15 expression profiles, HER2 and Chromosome 17 centromere gene status by fluorescence-in-situ-hybridization method.
  
  
  RESULTS
  Histological type was invasive ductal carcinoma in 90.2% of the tumors. p53, Ki67, GCDFP-15 mean positivity rates were 55.6%, 51.7%, and 3.2%, respectively. GCDFP-15 positivity was noted in 8 cases of which 6 were Cytokeratine 5/6 negative. The cut-off value for Cytokeratine 5/6 positivity was 5%. EGFR immunoreactivity was grouped into 0, 1+ as negative; 2+, 3+ as positive categories. Cytokeratine 5/6 was positive in 56,1%, EGFR was positive in 51.2% of the patients. The relation between Cytokeratine 5/6 and EGFR expression was statistically significant (p < 0.01). None of the cases showed HER2 amplification by fluorescence-in-situ-hybridization method.
  
  
  CONCLUSIONS
  GCDFP-15 alone is not a useful marker to detect the metastasis of basaloid type breast cancers. Cytokeratine 5/6 and EGFR expressions showed correlation so these markers are reliable to diagnose basaloid type tumors with a 5% cut-off value.
authors.affiliation: Department of Pathology, İzmir Tepecik Education and Research Hospital, İzmir, Turkey. emelozkok@yahoo.com
authors.forename: Emel Ebru
authors.initials: EE
authors.lastname: Pala
authors.forename: Ümit
authors.initials: Ü
authors.lastname: Bayol
authors.forename: Süheyla
authors.initials: S
authors.lastname: Cumurcu
authors.forename: Elif
authors.initials: E
authors.lastname: Keskın
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D002352:Carrier Proteins / Q000032:analysis / Q000096:biosynthesis; D066246:ErbB Receptors / Q000032:analysis / Q000096:biosynthesis; D005260:Female; D006023:Glycoproteins / Q000032:analysis / Q000096:biosynthesis; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D053555:Keratin-5 / Q000032:analysis / Q000096:biosynthesis; D053553:Keratin-6 / Q000032:analysis / Q000096:biosynthesis; D026901:Membrane Transport Proteins
chemical_list: D014408:Biomarkers, Tumor; D002352:Carrier Proteins; D006023:Glycoproteins; D053555:Keratin-5; D053553:Keratin-6; D026901:Membrane Transport Proteins; C488892:PIP protein, human; C512478:EGFR protein, human; D066246:ErbB Receptors