In fact, the presence of EGFR mutations (HR = 0.24, p = 0.001) and the use of EGFR TKIs after progression to chemotherapy (HR = 0.44, p = 0.03), were independently related to a better survival in stage IV NSCLC, (Additional file 5: Tables S5). The gene discussed is EGFR; the disease is non-small cell lung carcinoma.