title: Fluorescence in situ hybridization and immunohistochemical assays for HER-2/neu status determination: application to node-negative breast cancer.
abstract: BACKGROUND
  HER-2/neu (ERBB2) gene amplification and/or overexpression is a major event in human breast tumorigenesis. HER-2/neu gene alterations have been the most frequently assessed prognostic factors during the last 10 years in breast cancer and have recently emerged as a management decision tool and a therapeutic target. There is still controversy over the best method to determine whether a tumor is HER-2/neu positive. Because of the increasing demand for HER-2/neu gene status determination in clinical practice, we compared HER-2/neu gene alterations at the DNA level (gene amplification) and the protein level (overexpression) in a panel of patients with lymph node-negative breast cancer who had received local radiotherapy alone, with no adjuvant therapy.
  
  
  METHODS
  We tested 100 excised lymph node-negative breast tumors, using fluorescence in situ hybridization (FISH) with a biotinylated HER-2/neu DNA probe and immunohistochemical assays (IHC) with 2 different antibodies.
  
  
  RESULTS
  The FISH frequency of HER-2/neu gene amplification was 15%, and the IHC frequency of overexpression was 21%.
  
  
  CONCLUSIONS
  Although HER-2/neu amplification by FISH and HER-2/neu overexpression by IHC correlated well in this panel of lymph node-negative breast carcinomas, there were a number of discordant cases, pointing to the important need for determining HER-2/neu alteration for the future management of HER-2/neu-based clinical applications.
authors.affiliation: E0017 INSERM/Laboratoire d'Oncogénétique, Centre René Huguenin, 35 rue Dailly, F-92211 St Cloud, France.
authors.forename: P
authors.initials: P
authors.lastname: Onody
authors.forename: F
authors.initials: F
authors.lastname: Bertrand
authors.forename: F
authors.initials: F
authors.lastname: Muzeau
authors.forename: I
authors.initials: I
authors.lastname: Bièche
authors.forename: R
authors.initials: R
authors.lastname: Lidereau
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005784:Gene Amplification; D015870:Gene Expression; D018734:Genes, erbB-2; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D011379:Prognosis; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases