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

Table 1 Tumor node scores and cluster analysis for colon 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	10930	0.58	78.7%	I	T1N0	10930	0.58	78.7%
	T2N0	12931	1.16	74.3%		T1N1a	643	1.00	76.7%
IIa	T3N0	40338	1.74	66.7%	II	T2N0	12931	1.16	74.3%
IIb	T4aN0	5020	2.32	60.6%		T1N1b	325	1.42	65.8%
IIc	T4bN0	3088	2.90	45.7%		T2N1a	1270	1.58	72.1%
IIIa	T1N1a	643	1.00	76.7%		T3N0	40338	1.74	66.7%
	T2N1a	1270	1.58	72.1%		T1N2a	77	1.84	57.4%
	T1N1b	325	1.42	65.8%		T2N1b	896	2.00	67.7%
	T2N1b	896	2.00	67.7%	IIIa	T3N1a	8759	2.16	58.2%
	T1N2a	77	1.84	57.4%		T1N2b	27	2.26	55.0%
IIIb	T2N2a	300	2.41	66.6%		T4aN0	5020	2.32	60.6%
	T3N1a	8759	2.16	58.2%		T2N2a	300	2.41	66.6%
	T4aN1a	1311	2.74	52.2%		T3N1b	9107	2.58	51.7%
	T3N1b	9107	2.58	51.7%		T4aN1a	1311	2.74	52.2%
	T1N2b	27	2.26	55.0%		T2N2b	95	2.84	51.0%
	T2N2b	95	2.84	51.0%		T4bN0	3088	2.90	45.7%
	T4aN1b	1460	3.16	42.1%		T3N2a	5331	3.00	42.8%
	T3N2a	5331	3.00	42.8%	IIIb	T4aN1b	1460	3.16	42.1%
IIIc	T4aN2a	982	3.58	32.5%		T4bN1a	845	3.32	30.6%
	T3N2b	3235	3.42	30.4%		T3N2b	3235	3.42	30.4%
	T4bN1a	845	3.32	30.6%		T4aN2a	982	3.58	32.5%
	T4bN1b	929	3.74	25.4%		T4bN1b	929	3.74	25.4%
	T4bN2a	730	4.16	18.3%		T4aN2b	671	4.00	17.5%
	T4aN2b	671	4.00	17.5%	IIIc	T4bN2a	730	4.16	18.3%
	T4bN2b	653	4.58	12.9%		T4bN2b	653	4.58	12.9%

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

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.

Table 3 Summary of proposed tumor node metastasis staging system

Proposed TNM stage for colon cancer	TNcombinations	Proposed TNM stage for rectal cancer	TNcombinations
I	T1N0-1a	I	T1N0-1a
II	T1N1b-2a	II	T1N1b-2a
	T2N0-1b		T2N0-1b
	T3N0		T3N0
IIIa	T1N2b	IIIa	T1N2b
	T2N2a-2b		T2N2a-2b
	T3N1a-2a		T3N1a-2a
	T4aN0-1a		T4aN0-1a
	T4bN0
IIIb	T3N2b	IIIb	T3N2b
	T4aN1b-2b		T4aN1b-2b
	T4bN1a-1b		T4bN0-1b
IIIc	T4bN2a-2b	IIIc	T4bN2a-2b

TNM: Tumor node metastasis.