Is Cytology Reliable for Epidermal Growth Factor Receptor Gene Evaluation in Non-small Cell Lung Cancer?

Background: Epidermal growth factor receptor (EGFR) gene copy number has been proposed as predictor of response to epidermal growth factor receptor tyrosine kinase inhibitors in advanced non-small cell lung cancer (NSCLC). Methods: Cytologic and matched histologic samples from 33 primary non-small cell lung cancers were analyzed by fluorescence in situ hybridization (FISH) for epidermal growth factor receptor gene. Results: FISH was positive in 52% and negative in 35% of the 31 matched evaluable samples. Four of 31 (13%) cases were discordant (K = 0.736; p <0.001). Conclusion: Our data support the feasibility and reliability of epidermal growth factor receptor gene assessment by FISH on cytology.