Table 3. Correlation between preoperative serum CEA level and clinicopathological factors.

Characteristics	Number of patients [%]	CEA		P value
		Within the normal range	Elevated
Total	378	278	100
Age (years)
Mean ± SD	378	66.1±9.8	68.5±8.7	0.023*
Sex
Female	157 [42]	125 [80]	32 [20]	0.025*
Male	221 [58]	153 [69]	68 [31]
Smoking history
Never-smoker	195 [52]	157 [81]	38 [19]	0.002*
Ever-smoker	183 [48]	121 [66]	62 [34]
FEV1%
Mean ± SD	346	71.9 ±11.3	71.9±11.3	0.097
Unknown	32
Tumor size on chest CT (cm)
<2.0	253 [67]	190 [75]	63 [25]	0.386
>2.0	125 [33]	88 [70]	37 [30]
Tumor laterality
Right	217 [57]	154 [71]	63 [29]	0.197
Left	161 [43]	124 [77]	37 [23]
Primary lobe
Upper or middle lobe	265 [70]	195 [74]	70 [26]	0.978
Lower lobe	113 [30]	83 [73]	30 [27]
Histological type
Adenocarcinoma	345 [91]	263 [76]	81 [24]	<0.001*
Non-adenocarcinoma	34 [9]	15 [44]	19 [56]
Lymphatic permeation
Absent	248 [66]	197 [79]	51 [21]	<0.001*
Present	130 [34]	81 [62]	49 [38]
Visceral pleural invasion
Absent	315 [83]	244 [77]	71 [23]	<0.001*
Present	63 [17]	54 [60]	36 [40]
N status
N0	344 [91]	263 [76]	81 [24]	<0.001*
N1–3	34 [9]	15 [44]	19 [56]

Numbers in parentheses indicate percentages. *, significance level. SD, standard deviation; CEA, preoperative serum carcinoembryonic antigen level, normal upper limit at 5 ng/mL; FEV₁%, forced expiratory volume % in 1 s; CT, computed tomography; N, lymph node.