Table 1. Baseline clinical characteristics of the entire cohort based on the WBC count.

Variables	Cases [number, %]	Preoperative leukocytes [7×109/L, %]
		Non-leukocytosis	Leukocytosis	P value
Gender				0.006
Female	586 [19]	477 [20]	109 [15]
Male	2,510 [81]	1,911 [80]	599 [85]
Age [years]				0.732
<65	1,929 [62]	1,484 [62]	445 [63]
≥65	1,167 [38]	904 [38]	263 [37]
T stage				<0.001
T1	867 [28]	761 [32]	106 [15]
T2	402 [13]	382 [16]	20 [3]
T3	1,579 [51]	1,141 [48]	438 [62]
T4	248 [8]	104 [4]	144 [20]
Lymph node metastasis				0.339
N0	1,238 [40]	955 [40]	283 [40]
N1	960 [31]	748 [31]	212 [30]
N2	650 [21]	505 [21]	145 [20]
N3	248 [8]	180 [8]	68 [10]
TNM stage				<0.001
I	650 [21]	537 [22]	113 [16]
II	743 [24]	580 [24]	163 [23]
III	1,331 [43]	1,019 [43]	312 [44]
IV	372 [12]	252 [11]	120 [17]
Tumor location				0.239
Upper	88 [3]	73 [3]	15 [2]
Middle	2,234 [72]	1,730 [72]	504 [71]
Lower	774 [25]	585 [25]	189 [27]
Tumor type				0.309
Adenocarcinoma	279 [9]	222 [9]	57 [8]
Squamous	2,817 [91]	2,166 [91]	651 [92]
Tumor differentiation				0.969
Well	248 [8]	190 [8]	58 [8]
Moderate	2,415 [78]	1,865 [78]	550 [78]
Poor	433 [14]	333 [14]	100 [14]
Surgical procedure				0.075
Open	1,115 [36]	880 [37]	235 [33]
Video-assisted	1,981 [64]	1,508 [63]	473 [67]
Postoperative chemotherapy				<0.001
Yes	1,238 [40]	945 [40]	415 [60]
No	1,858 [60]	1,443 [60]	293 [40]
Anesthesia				0.383
General anesthesia	791 [26]	619 [26]	172 [24]
General and epidural anesthesia	2,305 [74]	1,769 [74]	536 [76]
Number of incisions				0.499
1	49 [2]	35 [1]	14 [2]
2	2,718 [88]	2,094 [88]	624 [88]
3	329 [10]	259 [11]	70 [10]