Table 2. Comparison of clinical/radiological characteristics and tumor markers of all the patients with solid solitary pulmonary nodules.

Characteristics	Overall cohort (n=588)	Training cohort (n=388)	Validation cohort (n=200)	P
Clinical characters
Male (%)	339 (57.7)	222 (57.2)	117 (58.5)	0.765
Age (year)	59.98±10.21	60.22±9.90	59.51±10.79	0.427
Smoking history (%)	259 (44.0)	173 (44.6)	86 (43.0)	0.713
Smoking quantity pieces-year	281.85±421.83	300.34±430.17	246.00±403.79	0.139
Previous malignancy	36 (6.1)	20 (5.2)	16 (8.0)	0.173
Position of lesion (%)				0.120
RUL	167 (28.4)	105 (27.1)	62 (31.0)
RML	55 (9.4)	31 (8.0)	24 (12.0)
RLL	125 (21.3)	85 (21.9)	40 (20.0)
LUL	136 (23.1)	88 (22.7)	48 (24.0)
LLL	105 (17.9)	79 (20.4)	26 (13.0)
Radiologic characters
Diameter (mm)	20.02±6.31	20.18±6.29	19.72±6.37	0.402
Spiculation (%)	332 (56.5)	211 (54.4)	121 (60.5)	0.156
Calcification (%)	30 (5.1)	17 (4.4)	13 (6.5)	0.269
Pleural indentation (%)	232 (39.5)	147 (37.9)	85 (42.5)	0.278
Lobulation (%)	408 (69.4)	274 (70.6)	134 (67.0)	0.367
Vascular convergence (%)	63 (10.7)	45 (11.6)	18 (9.0)	0.335
Tumor biomarker
CA125 (U/mL)	11.37±6.80	11.03±7.21	12.03±5.90	0.091
CEA (ìg/L)	4.08±9.43	4.24±9.16	3.76±9.97	0.556
CYFRA21-1 (ìg/L)	1.65±1.24	1.64±1.29	1.67±1.14	0.763
NSE (ìg/L)	10.59±4.56	10.56±4.72	10.66±4.27	0.800
SCC (ìg/L)	0.99±1.43	0.96±0.77	1.05±2.20	0.574
Histology diagnosis of malignancy (%)	462 (78.6)	308 (79.4)	154 (77.0)	0.505

RUL, right upper lobe; RML, right middle lobe; RLL, right lower lobe; LUL, left upper lobe; LLL, left lower lobe; CA125, carbohydrate antigen 125; CEA, carcinoembryonic antigen; CYFRA21-1, cytokeratin-19-fragment; NSE, neuron-specific enolase; SCC, squamous cell carcinoma antigen.