Table 5. Univariate analysis of potential factors affecting PFS.

Variables	HR (95% CI)	P
NLR (<2.57/≥2.57)	3.959 (2.083–7.525)	<0.001
Gender (male/female)	0.964 (0.545–1.704)	0.898
Smoking (never-smoker/current or ex-smoker)	2.32 (1.214–4.434)	0.011
Age (≤65/>65 years)	1.448 (0.795–2.638)	0.226
Pathological type (squamous carcinoma/adenocarcinoma)	0.302 (0.143–0.638)	0.002
TNM staging (stage III/IV)	1.174 (0.544–2.536)	0.682
Tumor Differentiation (well/moderately/poorly)	0.863 (0.550–1.353)	0.520

NLR, neutrophil-to-lymphocyte ratio; PFS, progression-free survival; TNM, The TNM Classification of Malignant Tumors.