Besides, as for the 4 cases with acquired EGFR-TKI resistance, two of them were E19Del+T790M positive both in tumor tissue and in plasma, one was L858R+T790M positive in tumor tissue but single L858R positive in plasma, and one was single L858R positive in tumor tissue but L858R+T790M positive in plasma. The gene discussed is EGFR; the disease is neoplasm.