Clinicopathologic factors affecting the progression-free survival of patients with advanced non-small-cell lung cancer after gefitinib therapy

Background: The aim of this study was to analyze the factors independent of epidermal growth factor (EGFR) gene mutations that affect the progression-free survival (PFS) of patients with advanced non-small-cell lung cancer (NSCLC) after gefitinib therapy. Patients and Methods: Eighty patients with advanced NSCLC between January 2003 and April 2010 at Kyoto University Hospital were analyzed for EGFR somatic mutations and treated with gefitinib. We adopted the peptide nucleic acid-locked nucleic acid polymerase chain reaction clamp method for determination of EGFR mutation status. To evaluate risk factors associated with PFS, Cox proportional hazards regression model with a step-down procedure was used. Proportional hazards assumptions were checked and satisfied; only those variables with statistically significant results in univariate analysis were included in a multivariate analysis. Results: The median PFS of patients with EGFR mutations were significantly longer than in patients with wild-type EGFR. The median PFS of patients after first-line gefitinib therapy was significantly longer than those who received treatment as a second-line therapy. The median PFS of patients over 75 years of age was significantly longer than in younger patients. Based on multivariate analysis, wild-type EGFR status and age < 75 years were significant and independent negative factors that affect PFS after gefitinib therapy. Conclusion: In this study, we showed the EGFR mutants and age > 75 years were good predictive factors for PFS after gefitinib therapy, suggesting that first-line gefitinib treatment for older patients is efficacious regardless of EGFR mutational status.