EGFR and lung cancer: In addition, several factors, such as the metastatic pattern, histological subtype, EGFR variant, presence of TP53 mutations, ECOG performance (PS) and smoking status have been shown to correlate with survival of stage IV EGFR+ lung cancer patients (4–9), but it is unknown whether the distribution and the prognostic importance of these parameters are similar between de novo and secondary metastatic cases.