title: Suitability of small bronchoscopic tumour specimens for lung cancer genotyping.
abstract: BACKGROUND
  Biomarker-driven clinical trials in advanced non-small cell lung cancer (NSCLC) usually accept biopsy specimens only, as cytology specimens are supposed to be more challenging due to low neoplastic cell content and suboptimal DNA quantity.
  
  
  OBJECTIVE
  We aimed to evaluate 2 aspects of bronchoscopic biopsy and cytology specimens: (1) the proportion of neoplastic cells and quantity of DNA extracted, and (2) the detection limit of the Scorpion amplification refractory mutation system on endoscopic samples obtained in daily clinical practice.
  
  
  METHODS
  We screened 679 patients with advanced-stage NSCLC for the presence of an activating EGFR mutation according to the guidelines of the European Society of Medical Oncology. Their diagnostic tumour tissue samples were characterized. A dilution experiment was performed to determine the minimal proportion of neoplastic cells for a reliable test result.
  
  
  RESULTS
  Surgical biopsies, bronchoscopic forceps biopsy samples and needle aspiration cytology specimens exhibited a median tumour cell proportion of 70 versus 30 versus 20% and a DNA quantity of 2,500 versus 1,610 versus 1,440 ng, respectively. The overall EGFR mutation rate was 11%, with no differences between different sample types. Dilution experiments showed that the detection limit depends on the type of mutation. A neoplastic cell content of at least 10 and 25% for exon 19 deletions and exon 21 L858R point mutation, respectively, was required for a true negative result.
  
  
  CONCLUSIONS
  Bronchoscopic forceps biopsy and needle aspiration cytology specimens are suitable for accurate EGFR mutation analysis using single-gene quantitative real-time polymerase chain reaction. Technologies with a better analytical sensitivity are evolving and should consider these endoscopic tumour specimens.
authors.affiliation: Respiratory Division, University Hospitals KU Leuven, Leuven, Belgium.
authors.forename: Christophe
authors.initials: C
authors.lastname: Dooms
authors.forename: Liesbet
authors.initials: L
authors.lastname: Vliegen
authors.forename: Sara
authors.initials: S
authors.lastname: Vander Borght
authors.forename: Jonas
authors.initials: J
authors.lastname: Yserbyt
authors.forename: Inge
authors.initials: I
authors.lastname: Hantson
authors.forename: Eric
authors.initials: E
authors.lastname: Verbeken
authors.forename: Els
authors.initials: E
authors.lastname: Wauters
authors.forename: Kristiaan
authors.initials: K
authors.lastname: Nackaerts
authors.forename: Vincent
authors.initials: V
authors.lastname: Ninane
authors.forename: Johan
authors.initials: J
authors.lastname: Vansteenkiste
authors.forename: Peter
authors.initials: P
authors.lastname: Vandenberghe
mesh_terms: D001999:Bronchoscopy; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics* / Q000473:pathology; D015331:Cohort Studies; D061765:Endoscopic Ultrasound-Guided Fine Needle Aspiration; D066246:ErbB Receptors / Q000235:genetics*; D005838:Genotype; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology; D009154:Mutation / Q000235:genetics*; D060888:Real-Time Polymerase Chain Reaction; D012680:Sensitivity and Specificity
chemical_list: D066246:ErbB Receptors