title: Diamond: immunohistochemistry versus sequencing in EGFR analysis of lung adenocarcinomas.
abstract: OBJECTIVE
  Identification of epidermal growth factor receptor (EGFR) mutations in lung adenocarcinomas is the single most important predictor of clinical response and outcome using EGFR tyrosine kinase inhibitors (TKIs). EGFR E746-A750del and L858R mutations are the most common gene alterations, also predicting the best clinical response to TKIs. We evaluated the accuracy of EGFR mutation-specific antibodies in a large cohort of lung adenocarcinomas, with different molecular settings and types of tissue samples.
  
  
  METHODS
  300 lung adenocarcinomas diagnosed on cytology (48 cell blocks), biopsy (157 cases) and surgical resections (95 cases) were selected. All cases were investigated for EGFR by sequencing and two mutation-specific antibodies (clone 6B6 for E746-A750del; clone 43B2 for L858R) were tested using an automated immunostainer. Discordant results were investigated by next-generation sequencing (NGS).
  
  
  RESULTS
  Overall sensitivity and specificity of mutant-specific antibodies were 58.6% and 98.0%, respectively, and they increased up to 84% and 100% if only tumours harbouring E746-A750del were considered. In 13 discordant cases, NGS confirmed immunohistochemistry results in eight samples.
  
  
  CONCLUSIONS
  The EGFR mutation-specific antibodies have a fair/good sensitivity and good/high specificity in identifying classic mutations, but they cannot replace molecular tests. The antibodies work equally well on biopsies and cell blocks, possibly permitting a rapid screening in cases with poor material.
authors.affiliation: Department of Oncology and Advanced Technologies, Operative Unit of Pathology, Azienda S Maria Nuova - IRCCS, Reggio Emilia, Italy.
authors.forename: Moira
authors.initials: M
authors.lastname: Ragazzi
authors.affiliation: Department of Oncology and Advanced Technologies, Operative Unit of Pathology, Azienda S Maria Nuova - IRCCS, Reggio Emilia, Italy.
authors.forename: Ione
authors.initials: I
authors.lastname: Tamagnini
authors.affiliation: Department of Oncology and Advanced Technologies, Operative Unit of Pathology, Azienda S Maria Nuova - IRCCS, Reggio Emilia, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Bisagni
authors.affiliation: Department of Oncology and Advanced Technologies, Operative Unit of Pathology, Azienda S Maria Nuova - IRCCS, Reggio Emilia, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Cavazza
authors.affiliation: Department of Oncology and Advanced Technologies, Operative Unit of Oncology, Azienda S. Maria Nuova - IRCCS, Reggio Emilia, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Pagano
authors.affiliation: Department of Oncology and Advanced Technologies, Operative Unit of Oncology, Azienda S. Maria Nuova - IRCCS, Reggio Emilia, Italy.
authors.forename: Licia
authors.initials: L
authors.lastname: Baldi
authors.affiliation: Department of Oncology and Advanced Technologies, Operative Unit of Oncology, Azienda S. Maria Nuova - IRCCS, Reggio Emilia, Italy.
authors.forename: Corrado
authors.initials: C
authors.lastname: Boni
authors.affiliation: Department of Oncology and Hematology, Division of Oncology, Azienda Ospedaliero-Universitaria Policlinico, Modena, Italy.
authors.forename: Flavia
authors.initials: F
authors.lastname: Cantile
authors.affiliation: Department of Oncology and Hematology, Division of Oncology, Azienda Ospedaliero-Universitaria Policlinico, Modena, Italy.
authors.forename: Fausto
authors.initials: F
authors.lastname: Barbieri
authors.affiliation: Department of Oncology and Advanced Technologies, Operative Unit of Molecular Biology, Azienda S. Maria Nuova - IRCCS, Reggio Emilia, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Nicoli
authors.affiliation: Department of Oncology and Advanced Technologies, Cervical Screening Unit, Azienda S. Maria Nuova - IRCCS, Reggio Emilia, Italy.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Sartori
authors.affiliation: Department of Medicine (DIMES), Anatomic Pathology Unit, Bellaria Hospital, University of Bologna, Bologna, Italy.
authors.forename: Dario
authors.initials: D
authors.lastname: de Biase
authors.affiliation: Department of Oncology and Advanced Technologies, Operative Unit of Pathology, Azienda S Maria Nuova - IRCCS, Reggio Emilia, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Gardini
authors.affiliation: Integrated Department of Diagnostic Laboratories, Section of Pathologic Anatomy, Azienda Ospedaliero-Universitaria Policlinico, Modena, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Rossi
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D004252:DNA Mutational Analysis / Q000379:methods*; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D005091:Exons; D005260:Female; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism; D008297:Male; D009154:Mutation; D012680:Sensitivity and Specificity
chemical_list: C512478:EGFR protein, human; D066246:ErbB Receptors
keywords: EGFR; IMMUNOHISTOCHEMISTRY; LUNG; LUNG CANCER