Table 1. The clinicopathological traits of patients in the training and the validation cohorts.

Patient characteristics			Training n (%)	Validationn (%)	P
Gender	Male		702 (68.6)	454 (68.0)	0.799
	Female		322 (31.4)	214 (32.0)
Age (ys)	<60		564 (55.1)	339 (50.7)	0.081
	≥60		460 (44.9)	329 (49.3)
Resection pattern	Distal		575 (56.2)	368 (55.1)	0.132
	Total		280 (27.3)	208 (31.1)
	Proximal		169 (16.5)	92 (13.8)
Lymphadenectomy	D1/D1+		550 (53.7)	368 (55.1)	0.578
	D2/D2+		474 (46.3)	300 (44.9)
Chemotherapy	No		649 (63.4)	348 (52.1)	<0.001
	Yes		375 (36.6)	320 (47.9)
Tumor location	Upper		252 (24.6)	187 (28.0)	0.002
	Middle		223 (21.8)	97 (14.5)
	Lower		529 (51.7)	373 (55.8)
	Whole		20 (2.0)	11 (1.6)
Tumor size (cm)	≤2		140 (13.7)	81 (12.1)	0.106
	2-5		487 (47.6)	300 (44.9)
	5-8		308 (30.1)	227 (34.0)
	>8		89 (8.7)	60 (9.0)
Macroscopic type	Type-0		161 (15.7)	90 (13.5)	0.050
	Type-1		38 (3.7)	29 (4.3)
	Type-2		443 (43.3)	273 (40.9)
	Type-3		333 (32.5)	225 (33.7)
	Type-4		49 (4.8)	51 (7.6)
Differentiation grade	Well		17 (1.7)	5 (0.7)	0.001
	Moderate		193 (18.8)	91 (13.6)
	Poor		814 (79.5)	572 (85.6)
pT stage	T1		188 (18.4)	122 (18.3)	0.055
	T2		120 (11.7)	87 (13.0)
	T3		106 (10.4)	106 (15.9)
	T4		610 (59.6)	353 (52.8)
pN stage	N0		310 (30.3)	206 (30.8)	0.378
	N1		199 (19.4)	115 (17.2)
	N2		191 (18.7)	114 (17.1)
	N3a		216 (21.1)	145 (21.7)
	N3b		108 (10.5)	88 (13.2)
M stage	M0		937 (91.5)	629 (94.2)	0.042
	M1		87 (8.5)	39 (5.8)
pTNM stage	I		221 (21.6)	141 (21.1)	0.240
	II		201 (19.6)	151 (22.6)
	III		515 (50.3)	337 (50.4)
	IV		87 (8.5)	39 (5.8)