In addition, the third-generation TKI drugs Osimertinib (AZD9291) and Rociletinib (CO-1686) have been developed to further benefit patients with primary TKI resistance caused by T790M mutation of EGFR. Therefore, detection of the EGFR mutation status of patients before treatment, and continuously monitoring the mutation of drug resistance genes during the treatment process is useful for the management of targeted drugs in NSCLC patients. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.