Table 4. Univariate and multivariate analyses of clinicopathological predictors of lymph node metastases.

Variables	Univariate analysis				Multivariate analysis
	HR	95% CI	P value		HR	95% CI	P value
Age (years)
<67	1				Not included in the multivariate model
>67	1.497	0.732–3.058	0.269
Sex
Female	1				Not included in the multivariate model
Male	1.658	0.818–3.367	0.16
Smoking history
Never-smoker	1				Not included in the multivariate model
Ever-smoker	1.209	0.595–2.457	0.6
CEA
Within the normal range	1				1
Elevated	4.113	1.999–8.461	<0.001*		3.019	1.386–6.578	0.005*
FEV1%
>70	1				Not included in the multivariate model
<70	1.464	0.698–3.068	0.683
Unknown
Tumor size on chest CT (cm)
<2.0	1				1
>2.0	2.844	1.392–5.811	0.004*		1.937	0.894–4.195	0.094
Tumor laterality
Right	1				Not included in the multivariate model
Left	1.161	0.521–2.179	0.938
Primary lobe
Upper or middle lobe	1				Not included in the multivariate model
Lower lobe	1.429	0.626–3.256	0.397
Histological type
Adenocarcinoma	1				Not included in the multivariate model
Non-adenocarcinoma	1.397	0.473–4.132	0.546
Lymphatic permeation
Absent	1				1
Present	11.072	4.450–27.550	<0.001*		8.417	3.252–21.785	<0.001*
Visceral pleural invasion
Absent	1				1
Present	2.288	1.034–5.059	0.041*		1.799	0.427–2.494	0.143

Numbers in parentheses indicate percentages. *, significance level. HR, hazard ratio; CI, confidence interval; CEA, preoperative serum carcinoembryonic antigen level, normal upper limit at 5 ng/mL; FEV₁%, forced expiratory volume percent in 1 s; CT, computed tomography.