title: Detecting EGFR alterations in clinical specimens-pitfalls and necessities.
abstract: We investigated the epidermal growth factor receptor (EGFR) status in early stage lung cancer in Southern Sweden, a population for which there are no previous reports on the EGFR mutation frequency. Three hundred fifty small cell lung cancers, adenocarcinomas (AC), squamous cell carcinomas (SqCC), and large cell carcinomas were analyzed using a combination of techniques for the analysis of protein expression, gene copy numbers, and mutations. Immunohistochemical (IHC) staining with antibodies for the EGFR mutations L858R and del E746-A750 revealed intratumoral heterogeneity and several discrepant cases when compared to mutation-specific polymerase chain reaction (PCR)-based analysis. The frequencies of these two mutations, when considering IHC staining with mutation-specific antibodies in a cohort of 298 cases and subsequent confirmation by PCR, were 10 % in AC and <2 % in SqCC. Furthermore, screening by sequencing of EGFR in a cohort of 52 lung AC and squamous carcinomas demonstrated a more diverse mutation spectrum, not covered by the mutation-specific antibodies. High expression of total EGFR protein was correlated to high gene copy numbers but did not reflect the mutational status of the tumors. We believe that the mutation spectra in a Southern Swedish population is too diverse to be covered by the mutation-specific antibodies, and we also raise some other issues regarding the use of the mutation-specific antibodies, for example concerning heterogeneous expression of the mutated protein, optimal antibody dilution, and discrepancies between staining results and PCR.
authors.affiliation: Department of Clinical Sciences, Division of Oncology, Lund University, Medicon Village, SE-223 81, Lund, Sweden.
authors.forename: Sofi
authors.initials: S
authors.lastname: Isaksson
authors.forename: Pär-Ola
authors.initials: PO
authors.lastname: Bendahl
authors.forename: Annette
authors.initials: A
authors.lastname: Salomonsson
authors.forename: Mats
authors.initials: M
authors.lastname: Jönsson
authors.forename: Monica
authors.initials: M
authors.lastname: Haglund
authors.forename: Alexander
authors.initials: A
authors.lastname: Gaber
authors.forename: Karin
authors.initials: K
authors.lastname: Jirström
authors.forename: Per
authors.initials: P
authors.lastname: Jönsson
authors.forename: Ake
authors.initials: A
authors.lastname: Borg
authors.forename: Leif
authors.initials: L
authors.lastname: Johansson
authors.forename: Johan
authors.initials: J
authors.lastname: Staaf
authors.forename: Maria
authors.initials: M
authors.lastname: Planck
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000235:genetics*; D004252:DNA Mutational Analysis / Q000379:methods*; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D018628:Gene Dosage; D018773:Genes, erbB-1 / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D017404:In Situ Hybridization, Fluorescence; D008175:Lung Neoplasms / Q000235:genetics; D008297:Male; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D046888:Tissue Array Analysis
chemical_list: C512478:EGFR protein, human; D066246:ErbB Receptors