Table 2.

Correlation between the interstitial fluid pressure (IFP) and clinicopathological factors

Factor	IFP (mean ± SD)	rho	r	p-value
CT findings
Solid (n = 148)	9.8 ± 6.8			<0.001
Part-solid (n = 63)	5.5 ± 4.7
Tumor size (CT)			0.309	<0.001
Size of the solid part (CT)			−0.077	0.27
Tumor size (pathological)			0.320	<0.001
SUVmax (n = 191)			0.475	<0.001
Histological types
SqCC (n = 52)	10.3 ± 7.5			<0.008
non-SqCC (n = 159)	7.8 ± 6.1
AD (n = 142)	7.7 ± 6.1
AdSq (n = 10)	7.3 ± 3.8
Others (n = 7)	11.2 ± 7.8
Lymphatic vessel invasion
ly-(n = 176)	7.7 ± 6.3			<0.001
ly+ (n = 35)	12.6 ± 6.2
Vascular vessel invasion
v− (n = 148)	7.2 ± 6.0			<0.001
v+ (n = 63)	11.6 ± 6.9
Pleural invasion		0.272		<0.001
0 (n = 159)	7.5 ± 5.9
1 (n = 28)	10.5 ± 7.5
2 (n = 7)	10.2 ± 4.3
3 (n = 17)	14.0 ± 8.1
Grade		0.305		<0.001
1 (n = 95)	6.5 ± 4.8
2 (n = 88)	9.7 ± 7.3
3 (n = 26)	11.0 ± 6.9
4 (n = 2)	20.5 ± 6.6
Ki-67 index	25 ± 19	0.303		<0.001
MVD	12.8 ± 8.1	0.061		0.38

SD: standard deviation; rho: Spearman rho; r: Pearson r; CT: computed tomography; AD: adenocarcinoma; SqCC: squamous cell carcinoma; AdSq: adenosquamous carcinoma; others: other histological types of lung cancer (small cell lung cancer [n = 1], alpha-feto protein producing lung cancer [n = 1], carcinoid [n = 2], large cell carcinoma with neuroendocrine feature [n = 2], and mucoepidermoid carcinoma [n = 1]); MVD: microvascular density