title: Molecular characterization of breast cancer in young Brazilian women.
abstract: OBJECTIVE
  To evaluate the distribution of molecular subtypes of breast tumors diagnosed in young Brazilian women and to analyze the frequency of loss of heterozygocity (LOH) in BRCA1 among different molecular subtypes of early-onset breast cancer.
  
  
  METHODS
  Samples from 72 cases of invasive breast carcinoma diagnosed in women aged between 19 and 40 years were evaluated using an immunohistochemical panel of biomarkers. Three intragenic BRCA1 locus microsatellites, D17S1322, D17S1323, and D17S855, were PCR amplified from matched normal (lymphocyte) and tumor DNAs for (LOH) analysis.
  
  
  RESULTS
  We found 13 cases (18%) that had an immunohistochemical profile consistent with being basal-like. Forty cases (55%) were luminal A type; 11% (8 cases) were luminal B type, 13% (9 cases) were HER2-overexpressing tumors and two cases were ER-/HER2- carcinomas lacking basal marker expression. Four of the 16 informative cases at D17S1322, one of the four informative cases at D17S855, and none of the five informative cases at D17S1323 displayed LOH (four basal-like and one Luminal A). Microsatellite instability (MSI) at D17S855 and D17S1322 was found in two cases (one a basal-like and one Luminal A).
  
  
  CONCLUSIONS
  In our study, basal-like tumor was the second most frequent molecular type among young Brazilian women and was only observed in women diagnosed under the age of 35 years. There was no significant difference of LOH at BRCA1 locus rates between basal-like breast tumors and not-basal-like breast tumors (p=0.62). LOH in BRCA1 and MSI in these breast cancers were not frequent but may indicate a small group of breast cancers with a specific molecular makeup.
authors.affiliation: Curso de Medicina, Centro Universitário Lusíada, UNILUS.
authors.forename: Leda Viegas de
authors.initials: LV
authors.lastname: Carvalho
authors.forename: Emílio Marcelo
authors.initials: EM
authors.lastname: Pereira
authors.forename: Lucien
authors.initials: L
authors.lastname: Frappart
authors.forename: Mathieu
authors.initials: M
authors.lastname: Boniol
authors.forename: Wanderley Marques
authors.initials: WM
authors.lastname: Bernardo
authors.forename: Vicente
authors.initials: V
authors.lastname: Tarricone
authors.forename: Sean
authors.initials: S
authors.lastname: Tavtigian
authors.forename: Melissa Caroline
authors.initials: MC
authors.lastname: Southey
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000097:blood; D001938:Brazil; D001943:Breast Neoplasms / Q000235:genetics*; D018270:Carcinoma, Ductal, Breast / Q000235:genetics*; D016009:Chi-Square Distribution; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D019398:Genes, BRCA1; D006801:Humans; D019656:Loss of Heterozygosity / Q000235:genetics*; D053842:Microsatellite Instability; D018295:Neoplasms, Basal Cell / Q000235:genetics; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics*; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases