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.