EGFR testing has become the consensus before epidermal growth factor-tyrosine kinase inhibitorrs (EGFR-TKIs) treatment in non-small cell lung cancer(NSCLC) patients.Malignant pleural effusion is the common clinical manifestation in NSCLC patients,and EGFR testing by using different methods in pleural effusion cells and free nucleic acids has good prospect for predicting the efficacy of EGFR-TKIs.