Table 4. Details of multivariate analysis for overall survival.

Variable	Hazard ratio	p value on Cox regression analysis
Elderly	0.586 (0.308–1.117)	0.105
Gender	1.671 (0.999–2.796)	0.051
ECOG PS	1.063 (0.358–3.154)	0.912
Smoking status	1.145 (0.636–2.059)	0.652
Liver metastasis	1.284 (0.777–2.119)	0.329
Brain metastasis	2.312 (1.262–4.236)	0.007
EGFR mutation type	0.425 (0.255–0.709)	0.001