Table 3. Cox multivariable analysis.

Variables	Hazard ratio (95% confidence interval)	P value
Sex	1.018 (0.490–2.116)	0.962
Smoking index	7.050 (3.079–16.143)	<0.001
Surgical resection method	2.822 (1.030–7.734)	0.044
Pathological TNM stage		<0.001
Stage I vs. stage II	6.039 (2.460–14.823)	<0.001
Stage I vs. stage III	3.145 (1.453–6.811)	0.004
Postoperative chemotherapy	0.211 (0.097–0.459)	<0.001