title: EGFR and KRAS quality assurance schemes in pathology: generating normative data for molecular predictive marker analysis in targeted therapy.
abstract: BACKGROUND
  The aim of this study was to compare the reproducibility of epidermal growth factor receptor (EGFR) immunohistochemistry (IHC), EGFR gene amplification analysis, and EGFR and KRAS mutation analysis among different laboratories performing routine diagnostic analyses in pathology in The Netherlands, and to generate normative data.
  
  
  METHODS
  In 2008, IHC, in-situ hybridisation (ISH) for EGFR, and mutation analysis for EGFR and KRAS were tested. Tissue microarray sections were distributed for IHC and ISH, and tissue sections and isolated DNA with known mutations were distributed for mutation analysis. In 2009, ISH and mutation analysis were evaluated. False-negative and false-positive results were defined as different from the consensus, and sensitivity and specificity were estimated.
  
  
  RESULTS
  In 2008, eight laboratories participated in the IHC ring study. In only 4/17 cases (23%) a consensus score of ≥75% was reached, indicating that this analysis was not sufficiently reliable to be applied in clinical practice. For EGFR ISH, and EGFR and KRAS mutation analysis, an interpretable result (success rate) was obtained in ≥97% of the cases, with mean sensitivity ≥96% and specificity ≥95%. For small sample proficiency testing, a norm was established defining outlier laboratories with unsatisfactory performance.
  
  
  CONCLUSIONS
  The result of EGFR IHC is not a suitable criterion for reliably selecting patients for anti-EGFR treatment. In contrast, molecular diagnostic methods for EGFR and KRAS mutation detection and EGFR ISH may be reliably performed with high accuracy, allowing treatment decisions for lung cancer.
authors.affiliation: Department of Pathology, Vrije Universteit Medical Centre, Amsterdam, The Netherlands. e.thunnissen@vumc.nl
authors.forename: Erik
authors.initials: E
authors.lastname: Thunnissen
authors.forename: Judith V M G
authors.initials: JV
authors.lastname: Bovée
authors.forename: Hans
authors.initials: H
authors.lastname: Bruinsma
authors.forename: Adriaan J C
authors.initials: AJ
authors.lastname: van den Brule
authors.forename: Winand
authors.initials: W
authors.lastname: Dinjens
authors.forename: Daniëlle A M
authors.initials: DA
authors.lastname: Heideman
authors.forename: Els
authors.initials: E
authors.lastname: Meulemans
authors.forename: Petra
authors.initials: P
authors.lastname: Nederlof
authors.forename: Carel
authors.initials: C
authors.lastname: van Noesel
authors.forename: Clemens F M
authors.initials: CF
authors.lastname: Prinsen
authors.forename: Karen
authors.initials: K
authors.lastname: Scheidel
authors.forename: Peter M
authors.initials: PM
authors.lastname: van de Ven
authors.forename: Roel
authors.initials: R
authors.lastname: de Weger
authors.forename: Ed
authors.initials: E
authors.lastname: Schuuring
authors.forename: Marjolijn
authors.initials: M
authors.lastname: Ligtenberg
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis / Q000235:genetics; D004252:DNA Mutational Analysis / Q000592:standards*; D066246:ErbB Receptors / Q000032:analysis / Q000235:genetics; D005188:False Negative Reactions; D005189:False Positive Reactions; D005784:Gene Amplification; D006801:Humans; D007150:Immunohistochemistry / Q000592:standards*; D017403:In Situ Hybridization / Q000592:standards*; D059021:Laboratory Proficiency Testing / Q000592:standards*; D008175:Lung Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000188:drug therapy / Q000235:genetics; D058990:Molecular Targeted Therapy; D009154:Mutation; D009426:Netherlands; D015588:Observer Variation; D018579:Patient Selection; D011237:Predictive Value of Tests; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D011785:Quality Assurance, Health Care / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D046888:Tissue Array Analysis / Q000592:standards*; D018631:ras Proteins / Q000235:genetics*
chemical_list: D014408:Biomarkers, Tumor; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; C512478:EGFR protein, human; D066246:ErbB Receptors; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins