Detection Of Epidermal Growth Factor Receptormutation Intransbronchial Biopsy Samplesof Adenocarcinoma

ObjectiveTo explore the feasibility of performing epidermal growth factor receptor mutation analysis on low-volume transbronchial biopsy samples byscorpions amplification refractory mutation system and by immunohistochemistry, and compare the sensitivity of these methods.Methods108patients with transbronchial biopsy tumor tissue samples and histologically confirmed adenocarcinoma, from January2009through December2011at Peking Union Medical College Hospital were enrolled. Clinical mannifestations were reviewed. All samples were microscopically examined for tumor cell ratio. EGFR mutation was assessed from DNA of the paraffin-embedded specimens by Scorpions ARMS, immunohistochemistry staining was performed using EGFR E746-A750del and21L858Rmutant antibody.ResultsIn108patients,92patientshad adequatespecimens left for analyses, and the detection rate was85.2%for low-volume biospsy samples.16patients had specimens with inadequate DNA for analyses, and were more frequently in male, the elder, samples with few tumor cells and biopsy less than4times and so on. Scorpions ARMS method were successfully performed in all92cases, and33EGFR mutations(35.8%) were detectedfrom DNA extracted from transbronchial biopsy tumor tissue samples, including16exon19in-frame deletion,17exon21point mutation(21L858R and21L861Q),1exon20insertion,1exon20point mutation(20S768I) and1with both19del and21L858Rmutations. The frequency of EGFR mutations was higher in female and non-smokers.21L858R mutation was more frequently in female than man(P=0.022). Infiltrating pattern under transbroncoscopyshowed higer mutation ratecompared with other patterns(P=0.043). Patients with EGFR mutations had longer overall survival than wildtype(P=0.036).16cases (17.8%)were scored positive for the exon19EGFR E746-A750mutant antibody, showed a sensitivity of73.3%and a specificity of93.3%compared with Scorpions ARMS, andthe concordance was moderate(kappa=0.649) between the two methods.19cases (21.4%) were scored positive for the exon21EGFR L858R mutant antibody, showed a sensitivity of93.3%and a specificity of93.2%compared with Scorpions ARMS, and the concordance was good (kappa=0.783).ConclusionEpidermal growth factor receptor mutation analysis can be performed on85.2%low-volume transbronchial biopsy samples by scorpions amplification refractory mutation system and by immunohistochemistry. Patients havefew biopsy times may have inadequate DNA for analyses. EGFR mutation status has relation with gender, tumor manifestations under transbronscopy, overall survival, but not with tumor differentiation and clinical stage. Immunohistochemistry with EGFR mutant-specific antibodies could be used as a screen to identify most mutations from low-volume biopsy samples.