The prognosis analysis of EGFR-TKI targeted treatment combined with chemotherapy in smokers with non-small cell lung cancer

Background: Administering epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) combined with chemotherapy in patients with non-small cell lung cancer (NSCLC) is a common treatment strategy. However, the prognostic factors for the EGFR-TKI combined with chemotherapy in smokers with NSCLC are still uncertain. Patients and methods: In this retrospective study, we enrolled patients with stage IV NSCLC diagnosed from June 2011 to March 2015 in two different university-affiliated hospitals in China. Basic characteristics including age, sex, smoking status, performance status, EGFR mutation status, tumor response, and progression-free survival (PFS) were recorded. Results: A total of 72 patients with stage IV NSCLC received treatment of EGFR-TKI combined with chemotherapy were enrolled. Survival analysis using the Kaplan-Meier method and log-rank test showed a significant difference when classifying the patients according to age and sex (P=0.0179). When stratifying the patients by sex, a significant difference was found between males and females (1.87 vs 4.87 months, P=0.0081). A reduced multivariate model developed using the backward variable selection method showed that ever smoking remained an independent poor prognostic factor for PFS (HR=3.814, 95% CI: 1.247-11.663, P=0.0189). After stratifying the patients by sex, ever smoking remained an independent poor prognostic factor for PFS in the female patients (HR=3.386, 95% CI: 1.015-11.298, P=0.0473). Conclusion: This study is the first to demonstrate that female ever smokers might have little prognosis if they have received EGFR-TKI combined with chemotherapy. Further large-scale studies are urgently needed to elucidate the mechanism.