title: HER2 testing by local, central, and reference laboratories in specimens from the North Central Cancer Treatment Group N9831 intergroup adjuvant trial.
abstract: OBJECTIVE
  To evaluate concordance between local and central laboratory HER2 testing results in patients from the North Central Cancer Treatment Group (NCCTG) N9831 adjuvant trial of trastuzumab.
  
  
  METHODS
  NCCTG N9831 is a randomized, phase III clinical trial comparing three drug regimens: doxorubicin/cyclophosphamide followed by paclitaxel with trastuzumab added concurrently, sequentially, or not at all as adjuvant therapy for women with HER2-positive resected breast cancer. Originally, patients were eligible if their tumors were HER2 positive by either local laboratory immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH). A protocol modification in 2002 made central laboratory testing mandatory, with additional testing of discordant cases conducted by a reference laboratory. Concordance between local and central laboratory, and level of agreement between central and reference laboratory HER2 findings in discordant cases were examined.
  
  
  RESULTS
  HER2 positivity was confirmed in 85.8% of 2,535 patients registered since March 2002. When local and central evaluation used the same methodology, concordance was 88.1% for FISH and 81.6% for a diagnostic test for presence of the HER2 protein. Among discordant cases examined at the reference laboratory, there was 94.3% agreement for IHC (0, 1+, 2+) and 95.2% agreement for FISH (not gene amplified).
  
  
  CONCLUSIONS
  There was a high degree of discordance between local and central testing for IHC and FISH, but a high degree of agreement between central and reference laboratories. These findings support the importance of using high-volume, experienced laboratories for HER2 testing to improve the process of selecting patients likely to benefit from trastuzumab therapy.
authors.affiliation: Mayo Clinic, 4500 San Pablo Rd, Jacksonville, FL 32224, USA. perez.edith@mayo.edu
authors.forename: Edith A
authors.initials: EA
authors.lastname: Perez
authors.forename: Vera J
authors.initials: VJ
authors.lastname: Suman
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Davidson
authors.forename: Silvana
authors.initials: S
authors.lastname: Martino
authors.forename: Peter A
authors.initials: PA
authors.lastname: Kaufman
authors.forename: Wilma L
authors.initials: WL
authors.lastname: Lingle
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Flynn
authors.forename: James N
authors.initials: JN
authors.lastname: Ingle
authors.forename: Daniel
authors.initials: D
authors.lastname: Visscher
authors.forename: Robert B
authors.initials: RB
authors.lastname: Jenkins
mesh_terms: D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D061067:Antibodies, Monoclonal, Humanized; D014408:Biomarkers, Tumor / Q000032:analysis; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D017024:Chemotherapy, Adjuvant; D005260:Female; D018734:Genes, erbB-2; D006801:Humans; D007150:Immunohistochemistry / Q000592:standards*; D017404:In Situ Hybridization, Fluorescence / Q000592:standards*; D007753:Laboratories / Q000592:standards; D018579:Patient Selection; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D000068878:Trastuzumab
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D014408:Biomarkers, Tumor; D000068878:Trastuzumab