Table 2. Comparison of 3-year OS rates among different stages according to the 6^th and the 7^th UICC-AJCC TNM staging systems.

Variable	6th edition				7th edition			P value
	Total (n)	Survival (n)	3-y OS (%)		Total (n)	Survival (n)	3-y OS (%)
T stage								0.000
Tis	0				0	–	–
T1	72	59	81.9		–	–	–
T1a	–				21	18	85.7
T1b	–				51	40	78.4
T2	195	131	67.2		195	131	67.2
T3	480	261	54.4		480	261	54.4
T4	19	5	26.3		–	–	–
T4a	–				13	5	38.5
T4b	–				6	1	16.7
N stage								0.000
N0	359	271	75.5		359	271	75.5
N1	407	185	45.5		135	88	65.2
N2	–				184	73	39.7
N3	–				88	24	27.3
M stage								0.000
M0	686	433	63.1		766	456	59.5
M1a	80	23	28.8

UICC-AJCC, Union for International Cancer Control–American Joint Committee on Cancer; TNM, tumor, node, metastasis; OS, overall survival.