Table 1.

Clinical characteristics of 1,575 patients with NSCLC.

Characteristics		Number	Percentage (%)
Gender	Male	1090	69.2
	Female	485	30.8
Age	<70 years	1417	90.0
	≤70 years	158	10.0
Smoking history	Yes	1012	64.3
	No	563	35.7
The type of histology	Squamous cell carcinoma	914	58.0
The type of histology	Non-Squamous cell carcinoma	661	42.0
	Stage I	852	54.0
Clinical stage	Stage II	330	21.0
	Stage III	393	25.0
	N0	902	57.3
N Stage	N1	322	20.4
	N2	351	22.3
Number of LNs resected	≤6	649	41.2
Number of LNs resected	>6	926	58.8
	0	897	57.3
Number of metastatic LNs	1~2	437	27.7
	>2	241	15.3
	≤25%	270	39.8
Metastatic ratio of LNs	25~50%	201	29.6
Metastatic ratio of LNs	50~75%	80	11.8
	>75	127	18.7
	No metastatic LNs	902	57.3
*The distribution area of metastatic LNs^{^}**	N1	322	20.4
	Skip N2	161	10.2
	Continue N2	190	12.1

↵* Skip N2 only included metastatic LNs in the mediastinum and without metastatic LNs in the region of N1; continue N2 included metastatic LNs in the mediastinum and the region of N1.