Efficacy of bronchoscopic biopsy for the detection of epidermal growth factor receptor mutations and anaplastic lymphoma kinase gene rearrangement in lung adenocarcinoma

BACKGROUND To explore the efficacy of bronchoscopic biopsy for the detection of epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) gene rearrangement in lung adenocarcinoma. METHODS All patients with bronchoscopic biopsy-proven lung adenocarcinoma at the Peking Union Medical College Hospital from January 2009 to November 2011 were enrolled. Scorpion amplification refractory mutation system (ARMS) was used to detect EGFR gene mutations and fluorescence in situ hybridization (FISH) to detect ALK rearrangement. The correlation of immunohistochemistry (IHC) results with standard methods for EGFR mutation status and ALK rearrangement were checked. RESULTS Bronchoscopic specimens were successfully used to detect EGFR mutation and ALK rearrangement with success rates of 85.2% and 71.3%, respectively, in non-small cell lung cancer patients. EGFR analysis by ARMS yielded a positive result in 35.8% (33/92) and positive ALK rearrangement was detected by FISH in 7.8% (6/77) of cases. It was more likely to be unsuccessful in patients with tumor cells less than 100/high power field and the ratio tumor numbers in 0-10%. In EGFR-IHC, the sensitivity and specificity of E746-A750 deletions were 73.3% (11/15) and 93.3% (70/75), respectively, and those of L858R were 93.3% (14/15) and 93.2% (69/74), respectively. In ALK-IHC, the sensitivity and specificity were 50% (3/6) and 100% (71/71), respectively. CONCLUSIONS Small bronchoscopic specimens could achieve higher successful detection rates via EGFR mutation and ALK gene rearrangement.