TNM staging of colorectal cancer should be reconsidered by T stage weighting

Table 2 Tumor node scores and cluster analysis for rectal cancer

AJCC 7th edTNM stage	TNcombinations	Patients(n)	TN score	5-yr OS	ProposedTNM stage	TNcombinations	Patients(n)	TN score	5-yr OS
I	T1N0	3348	0.61	81.4%	I	T1N0	3348	0.61	81.4%
	T2N0	6613	1.22	75.7%		T1N1a	274	1.00	75.7%
IIa	T3N0	10615	1.83	64.0%	II	T2N0	6613	1.22	75.7%
IIb	T4aN0	818	2.44	55.7%		T1N1b	170	1.39	75.9%
IIc	T4bN0	769	3.05	44.7%		T2N1a	923	1.61	72.7%
IIIa	T1N1a	274	1.00	75.7%		T1N2a	62	1.78	73.8%
	T2N1a	923	1.61	72.7%		T3N0	10615	1.83	64.0%
	T1N1b	170	1.39	75.9%		T2N1b	641	2.00	68.9%
	T2N1b	641	2.00	68.9%	IIIa	T1N2b	24	2.17	53.2%
	T1N2a	62	1.78	73.8%		T3N1a	2758	2.22	55.4%
IIIb	T2N2a	302	2.39	58.2%		T2N2a	302	2.39	58.2%
	T3N1a	2758	2.22	55.4%		T4aN0	818	2.44	55.7%
	T4aN1a	218	2.83	53.2%		T3N1b	3029	2.61	49.7%
	T3N1b	3029	2.61	49.7%		T2N2b	120	2.78	41.7%
	T1N2b	24	2.17	53.2%		T4aN1a	218	2.83	53.2%
	T2N2b	120	2.78	41.7%		T3N2a	1964	3.00	42.5%
	T4aN1b	262	3.22	43.9%		T4bN0	769	3.05	44.7%
	T3N2a	1964	3.00	42.5%	IIIb	T4aN1b	262	3.22	43.9%
IIIc	T4aN2a	199	3.61	44.3%		T3N2b	1791	3.39	32.0%
	T3N2b	1791	3.39	32.0%		T4bN1a	201	3.44	24.4%
	T4bN1a	201	3.44	24.4%		T4aN2a	199	3.61	44.3%
	T4bN1b	222	3.83	24.0%		T4bN1b	222	3.83	24.0%
	T4bN2a	156	4.22	18.5%		T4aN2b	198	4.00	24.5%
	T4aN2b	198	4.00	24.5%	IIIc	T4bN2a	156	4.22	18.5%
	T4bN2b	152	4.61	12.3%		T4bN2b	152	4.61	12.3%

OS: Observed survival; AJCC: American Joint Committee on Cancer; TNM: Tumor node metastasis.