Several previous studies of NSCLC have demonstrated a discrepancy of EGFR mutation status between the primary tumor and the corresponding metastatic lesions [33–35], and it has been suggested that the EGFR mutation status in the latter may be more associated with favorable efficacy of EGFR-TKI treatment than that in the former [35]. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.