S1.

Correlation between clinicopathological characteristics and pN stage of GC patients (N=7,620)

Characteristics	pN stage (n)					χ2	P
	N0	N1	N2	N3a	N3b
GC, gastric cancer; TG, total gastrectomy; DG, distal gastrectomy; PG, proximal gastrectomy; ELN, examined lymph node. The eighth edition of TNM classification for GC was adopted for postoperatively pathological stages of all included patients.
Gender						15.823	0.003
Male	1,985	986	1,065	932	410
Female	808	378	422	406	228
Age at surgery (year)						26.076	<0.001
<60	1,522	656	732	715	361
≥60	1,271	708	755	623	277
Tumor location						210.795	<0.001
Upper third	741	410	444	311	117
Middle third	507	224	260	314	169
Lower third	1,389	642	636	584	236
>2/3 stomach	156	88	147	129	116
Tumor size (cm)						636.873	<0.001
≤4.0	1,812	636	592	431	155
>4.0	981	728	895	907	483
Lauren classification						152.489	<0.001
Intestinal	1,363	620	610	438	184
Diffuse	1,430	744	877	900	454
Type of gastrectomy						363.556	<0.001
TG	435	250	355	407	294
DG	1,739	767	768	692	264
PG	619	347	364	239	80
pT stage						1,334.542	<0.001
T1	792	84	51	18	0
T2	637	267	259	177	69
T3	365	256	286	225	116
T4a	915	674	785	780	374
T4b	84	83	106	138	79
ELN count						745.581	<0.001
<16	1,031	495	522	244	0
16−30	1,203	613	646	762	258
>30	559	256	319	332	380