Table 1.

Description of the study population.

	Test set			Validation set
	Colorectal cancer	Healthy controls	P value	Colorectal cancer	Healthy	P value
N (%)	72 (49.7%)	71 (50.3%)		34 (49.3%)	35 (50.7%)
Female	40 (55.6%)	37 (52.1%)	0.680	15 (46.9%)	19 (51.4%)	0.711
Male	32 (44.4%)	34 (47.9%)	0.680	17 (53.1%)	18 (48.6%)	0.711
Age, mean (SD)	69.8 (10.3)	69.7 (10.6)	0.857	69.5 (10.1)	69.5 (9.1)	0.483
Pack-years, mean (SD)	14.7 (16.4)	12.1 (16.7)	0.899	16.0 (19.2)	6.5 (9.6)	0.009
BMI, mean (SD)	27.3 (4.1)	27.3 (4.1)	0.568	27.6 (4.2)	27.6 (3.5)	0.383
Diabetes	7 (9.7%)	3 (4.2%)	0.198	1 (2.9%)	1 (2.9%)	0.983
Hb, mean (SD)	12.2 (2.2)			12.4 (2.0)
CEA, mean (min–max)	67.5 (1.0–1068.0)			68.5 (1.0–1848.0)
Median	4.0			3.0
Tumour localisation, n (%)
RCC	30 (41.7%)			15 (44.1%)
LCC	22 (30.6%)			11 (32.4%)
RC	20 (27.8%)			8 (23.5%)
Tumour stage, n (%)	54 (75.0%)			30 (88.2%)
T1	0 (0%)			2 (6.7%)
T2	11 (20.4%)			5 (16.7%)
T3	35 (64.8%)			20 (66.7%)
T4	8 (14.8%)			3 (10.0%)
Node stage, n (%)	57 (79.2%)			29 (85.3%)
N0	40 (70.2%)			14 (48.3%)
N1	12 (21.1%)			8 (27.6%)
N2	5 (8.8%)			7 (24.1%)
Metastasis stage, n (%)	68 (94.4%)			33 (97.1%)
M0	53 (77.9%)			28 (84.8%)
M1	15 (22.1%)			5 (15.2%)
Stage (AJCC)
I	6 (8.3%)			2 (5.9%)
II	37 (51.4%)			15 (44.1%)
III	13 (18.1%)			12 (35.3%)
IV	16 (22.2%)			5 (14.7%)

SD standard deviation, BMI body mass index (kg/m²), Hb haemoglobin (g/dl), CEA carcinoembryonic antigen (µg/l), RCC right colon cancer, LCC left colon cancer, RC rectal cancer, T tumour, N Node, M metastasis, AJCC American joint committee on Cancer. Bold value = p < 0.05.

Χ² test was used for categorical variables and t test for continous variables.