Table 1.

Characteristics of patients in the training and validation cohorts

Variables	Training cohort (n = 264)		Validation cohort (n = 216)		P
	n	%	n	%
Age					0.417
≤60 years	160	60.6	123	56.9
>60 years	104	39.4	93	43.1
Age (years), median (IQR)	57 (49–65)		59 (51–65)		0.443
Sex					0.571
Male	186	70.5	147	68.1
Female	78	29.5	69	31.9
ECOG PS					0.840
0	190	72.0	158	73.1
1	68	25.8	55	25.5
2	6	2.2	3	1.4
CEA level					0.158
Normal	216	81.8	187	86.6
Elevated	48	18.2	29	13.4
CA 19-9 level					0.385
Normal	223	84.5	176	81.5
Elevated	41	15.5	40	18.5
Tumour location					0.690
Fundus of the stomach	61	23.1	43	19.9
Body of the stomach	49	18.6	43	19.9
Antrum of the stomach	154	58.3	130	60.2
Tumour size					0.299
≤4 cm	147	55.7	110	50.9
>4 cm	117	44.3	106	49.1
Tumour grade					0.725
Grade 1	18	6.8	12	5.6
Grade 2	54	20.5	44	20.4
Grade 3	169	64.0	135	62.5
Grade 4	23	8.7	25	11.5
Lauren type					0.530
Intestinal type	120	45.5	92	42.6
Diffuse and mixed type	144	54.5	124	57.4
Depth of invasion					0.307
T1	48	18.2	30	13.9
T2	24	9.1	17	7.9
T3	29	11.0	19	8.8
T4a	143	54.2	124	57.4
T4b	20	7.5	26	12.0
Lymph node metastasis					0.803
N0	112	42.4	81	37.5
N1	50	18.9	40	18.5
N2	42	15.9	38	17.6
N3a	37	14.0	34	15.7
N3b	23	8.8	23	10.7
Distant metastasis					0.999
M0	253	95.8	207	95.8
M1	11	4.2	9	4.2
TNM stage					0.310
Stage I	54	20.5	30	13.9
Stage II	74	28.0	66	30.5
Stage III	125	47.3	111	51.4
Stage IV	11	4.2	9	4.2
Adjuvant chemotherapy					0.626
Yes	161	61.0	127	58.8
No	103	39.0	89	41.2

The comparisons of continuous age variables between two groups are performed using a two-sided Mann–Whitney U test, and the rest variables are compared using a two-sided χ² or Fisher’s exact test.

IQR interquartile range, ECOG PS Eastern Cooperative Oncology Group performance status, CEA carcinoembryonic antigen, CA carbohydrate antigen, TNM tumour-node-metastasis.