title: Markers of subtypes in inflammatory breast cancer studied by immunohistochemistry: prominent expression of P-cadherin.
abstract: BACKGROUND
  Inflammatory breast cancer (IBC) is a distinct and aggressive form of locally-advanced breast cancer with high metastatic potential. In Tunisia, IBC is associated with a high death rate. Among the major molecular subtypes, basal breast carcinomas are poorly differentiated, have metastatic potential and poor prognosis, but respond relatively well to chemotherapy. The aim of this study was to determine the distribution of molecular subtypes in IBC and identify factors that may explain the poor prognosis of IBC.
  
  
  METHODS
  To determine breast cancer subtypes we studied by immunohistochemistry the expression of 12 proteins in a series of 91 Tunisian IBC and 541 non-IBC deposited in tissue microarrays.
  
  
  RESULTS
  We considered infiltrating ductal cases only. We found 33.8% of basal cases in IBC vs 15.9% in non-IBC (p < 0.001), 33.3% of ERBB2-overexpressing cases in IBC vs 14.5% in non-IBC (p < 0.001), and 29.3% of luminal cases in IBC vs 59.9% in non-IBC (p < 0.001). The most differentially-expressed protein between IBCs and non-IBCs was P-cadherin. P-cadherin expression was found in 75.9% of all IBC vs 48.2% of all non-IBC (p < 0.001), 95% of IBC vs 69% of non-IBC (p = 0.02) in basal cases, and 82% of IBC vs 43% of non-IBC (p < 0.001) in luminal cases. Logistic regression determined that the most discriminating markers between IBCs and non-IBCs were P-cadherin (OR = 4.9, p = 0.0019) MIB1 (OR = 3.6, p = 0.001), CK14 (OR = 2.7, p = 0.02), and ERBB2 (OR = 2.3, p = 0.06).
  
  
  CONCLUSIONS
  Tunisian IBCs are characterized by frequent basal and ERBB2 phenotypes. Surprisingly, luminal IBC also express the basal marker P-cadherin. This profile suggests a specificity that needs further investigation.
authors.affiliation: Centre de Recherche en Cancérologie de Marseille, Département d'Oncologie Moléculaire, UMR599 Inserm, Marseille, France. azza.benhamida@gmail.com
authors.forename: Azza
authors.initials: A
authors.lastname: Ben Hamida
authors.forename: Intidhar S
authors.initials: IS
authors.lastname: Labidi
authors.forename: Karima
authors.initials: K
authors.lastname: Mrad
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Charafe-Jauffret
authors.forename: Saïda
authors.initials: S
authors.lastname: Ben Arab
authors.forename: Benjamin
authors.initials: B
authors.lastname: Esterni
authors.forename: Luc
authors.initials: L
authors.lastname: Xerri
authors.forename: Patrice
authors.initials: P
authors.lastname: Viens
authors.forename: François
authors.initials: F
authors.lastname: Bertucci
authors.forename: Daniel
authors.initials: D
authors.lastname: Birnbaum
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Jacquemier
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000737:chemistry* / Q000145:classification / Q000150:complications / Q000473:pathology; D015820:Cadherins / Q000032:analysis*; D018270:Carcinoma, Ductal, Breast / Q000737:chemistry* / Q000145:classification / Q000150:complications / Q000556:secondary; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000150:complications; D008875:Middle Aged; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism*
chemical_list: D014408:Biomarkers, Tumor; D015820:Cadherins; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; C508053:ERBB2 protein, human