Table 2.

The AJCC 8th edition ypTNM staging definitions and the modified ypTNM staging definitions for gastric cancer after neoadjuvant therapy, with cross‐tabulation of stage distributions

Definitions for ypT, ypN
ypT category (primary tumor)
T1	Tumor invades the lamina propria, muscularis mucosae, or submucosa
T2	Tumor invades the muscularis propria
T3	Tumor penetrates the subserosal connective tissue without invasion of the visceral peritoneum or adjacent structures
T4	Tumor invades the serosa (visceral peritoneum) or adjacent structures
T4a	Tumor invades the serosa (visceral peritoneum)
T4b	Tumor invades adjacent structures/organs
ypN category (regional lymph nodes)
N0	No regional lymph node metastasis
N1	Metastasis in one or two regional lymph nodes
N2	Metastasis in three to six regional lymph nodes
N3	Metastasis in seven or more regional lymph nodes
N3a	Metastasis in seven to 15 regional lymph nodes
N3b	Metastasis in 16 or more regional lymph nodes

ypTNM staging (AJCC 8th)					Modified ypTNM staging
	N0	N1	N2	N3		N0	N1	N2	N3
T1	I	I	II	II	T1	IA	II	IIIA	IIIA
T2	I	II	II	III	T2	IB	II	IIIA	IIIA
T3	II	II	III	III	T3	IB	II	IIIA	IIIB
T4a	II	III	III	III	T4a	II	II	IIIA	IIIB
T4b	III	III	III	III	T4b	IIIA	IIIA	IIIA	IIIB

	Development cohort					Validation cohort
Systems	IA	IB	II	IIIA	IIIB	IA	IB	II	IIIA	IIIB
I	93	92	42	0	0	17	19	3	0	0
II	0	173	364	61	0	0	26	50	14	0
III	0	0	149	454	363	0	0	17	52	68

Abbreviation: AJCC 8th, American Joint Committee on Cancer 8th edition.