As far as we known, our study, for the first time, demonstrated a survival benefit of combining targeted therapy over monotherapy with erlotinib as second-line treatment for advanced NSCLC in terms of OS, PFS and ORR, and sub-group analysis based on phases of trials, EGFR-status and KRAS status also showed that there was a tendency to improve PFS and OS in combining targeted therapy, except that PFS for patients with EGFR-mutation or wild type KRAS favored erlotinib monotherapy. The gene discussed is KRAS; the disease is non-small cell lung carcinoma.