EGFR and adenocarcinoma: In a multivariate analysis, patients with adenocarcinoma (Hazard Ratio 5.650, 95% CI 2.223 to 14.362, p < 0.001, Fig. 2a), recurrent disease (Hazard Ratio 1.976, 95% CI 1.291 to 3.025, p = 0.002, Fig. 2b), or receiving EGFR-TKI therapy (Hazard Ratio 2.525, 95% CI 1.748 to 3.646, p < 0.001, Fig. 2c) had a significantly longer survival than those with squamous cell carcinoma, metastatic disease, or without EGFR-TKI therapy (Table 3).