Objective:Non-small cell lung cancer(NSCLC)patients with epidermal growth factor receptor(EGFR)-activating mutations have higher response rate and more prolonged survival following treatment with single-agent EGFR tyrosine kinase inhibitor(EGFR-TKI)compared with patients with wild-type EGFR.However,all patients treated with reversible inhibitors develop acquired resistance over time.The mechanisms of resistance are complicated.The lack of established therapeutic options for patients after a failed EGFR-TKI treatment poses a great challenge to physicians in managing this group of lung cancer patients.This study evaluates the influence of EGFR-TKI retreatment following chemotherapy after failure of initial EGFR-TKI within at least 6 months on NSCLC patients.Methods:The data of 27 patients who experienced treatment failure from their initial use of EGFR-TKI within at least6 months were analyzed.After chemotherapy,the patients were retreated with EGFR-TKI(gefitinib 250 mg qd or erlotinib150 mg qd),and the tumor progression was observed.The patients were assessed for adverse events and response to therapy.Targeted tumor lesions were assessed with CT scan.Results:Of the 27 patients who received EGFR-TKI retreatment,1(3.7%)patient was observed in complete response(CR),8(29.6%)patients in partial response(PR),14(51.9%)patients in stable disease(SD),and 4(14.8%)patients in progressive disease(PD).The disease control rate(DCR)was 85.2%(95%CI:62%-94%).The median progression-free survival(m PFS)was 6 months(95%CI:1-29).Of the 13 patients who received the same EGFR-TKI,1 patient in CR,3 patients in PR,8 patients in SD,and 2 patients in PD were observed.The DCR was 84.6%,and the m PFS was 5 months.Of the 14 patients who received another EGFR-TKI,no patient in CR,6 patients in PR,6 patients in SD,and 2 patients in PD were observed.The DCR was 85.7%,and the m PFS was 9.5 months.Significant difference was found between the two groups in PFS but not in response rate or DCR.Conclusion:Retreatment of EGFR-TKIs can be considered an option after failure of chemotherapy for patients who were previously controlled by EGFR-TKI treatment. Objective: Non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) -activating mutations have higher response rate and more prolonged survival following treatment with single-agent EGFR tyrosine kinase inhibitor (EGFR-TKI) compared with patients with wild-type EGFR. However, all patients treated with reversible inhibitors develop acquired resistance over time. These mechanisms of resistance are complicated. The lack of established therapeutic options for patients after a failed EGFR-TKI treatment poses a great challenge to physicians in managing this group of lung cancer patients. This study evaluates the influence of EGFR-TKI retreatment following chemotherapy after failure of initial EGFR-TKI within at least 6 months on NSCLC patients. Methods: The data of 27 patients who experienced treatment failure from their initial use of EGFR-TKI within at least 6 months were analyzed. After chemotherapy, the patients were retreated with EGFR-TKI (gefitinib 250 mg qd or erlotinib 15 0 mg qd), and the tumor progression was observed. The patients were assessed for adverse events and response to therapy. Targeted tumor lesions were assessed with CT scan. Results: Of the 27 patients who received EGFR-TKI retreatment, 1 (3.7% patients in stable disease (SD), and 4 (14.8%) patients in progressive disease (PD) The disease control rate (DCR) was 85.2% (95% CI: 62% -94%). The median progression-free survival (m PFS) was 6 months The patients received the same EGFR-TKI, 1 patient in CR, 3 patients in PR, 8 patients in SD, and 2 patients in PD were observed. The DCR was 84.6%, and the m PFS was 5 months. Of the 14 patients who Received another EGFR-TKI, no patient in CR, 6 patients in PR, 6 patients in SD, and 2 patients in PD were observed. The DCR was 85.7%, and the m PFS was 9.5 months. groups in PFS but not in response rate or DCR.Conclusion: Retreatment of EGFR-TKIs can be considered an option after failure of chemotherapy for patients who previously been controlled by EGFR-TKI treatment.