Kaplan-Meier curves for progression-free survival (PFS) and overall survival(OD). Kaplan-Meier curves for progression-free survival are shown for the overall population (Panel A) and patients who received only 4 cycles of first-line chemotherapy (Panel C), patients who were positive for the EGFR mutation (Panel E), and patients with EGFR mutation wide type (Panel G). Kaplan-Meier curves for overall survivaol are shown for the overall population (Panel B) and patients who reeived ony 4 cycles of first-line chemotherapy (Panel D), patients who were positive for the EGFR utation (Panel F), and patients with EGFR mutation wide type (Panel H). Hazard ratios were calculated with the use of a Cox proportional-hazards model, with sex smoking history (never smoker or ever smoker), and histology (adeocarvinoma or non-adenocarcinoma) as covariates.