Comparison of the eighth version of the American Joint Committee on Cancer manual to the seventh version for colorectal cancer: A retrospective review of our data

Table 1 Comparison of the tumor-node-metastasis stages between the 7^th edition and the 8^th edition

7th edition	8th edition
Tx: Primary tumor cannot be assessed	Tx: Primary tumor cannot be assessed
T0: No evidence of primary tumor	T0: No evidence of primary tumor
Tis: Carcinoma in situ, limited to intraepithelial or invasive lamina propria	Tis: Carcinoma in situ, limited to intraepithelial or invasive lamina propria
T1: Tumor invading submucosa	T1: Tumor invading submucosa
T2: Tumor invading the muscularis propria	T2: Tumor invading the muscularis propria
T3: Tumor penetrating the muscularis propria and arriving at colorectal fat tissue	T3: Tumor penetrating the muscularis propria and arriving at colorectal fat tissue
T4: Tumor directly invading other organs or structures	T4: Tumor directly invading other organs or structures
T4a: Tumor penetrating visceral peritoneum	T4a: Tumor penetrating visceral peritoneum
T4b: Tumor directly invading or adhering to other organs or structures	T4b: Tumor directly invading or adhering to other organs or structures
Nx: Regional lymph nodes cannot be assessed	Nx: Regional lymph nodes cannot be assessed
N0: No lymph node metastasis and no tumor deposits (TD)	N0: No lymph node metastasis and no TD
N1: 1-3 lymph nodes metastases	N1: 1-3 lymph nodes metastases
N1a: 1 lymph node metastases	N1a: 1 lymph node metastases
N1b: 2-3 lymph nodes metastases	N1b: 2-3 lymph nodes metastases
N1c: Although there was no regional lymph node metastasis, TDs were submucosal, mesangial, or peritoneum-covered para-colorectal tissue.	N1c: Although there was no regional lymph node metastasis, TDs were submucosal, mesangial or peritoneum-covered para-colorectal tissue.
N2: More than or equal to 4 lymph node metastases	N2: More than or equal to 4 lymph node metastases
N2a: 4-6 regional lymph node metastases	N2a: 4-6 regional lymph node metastases
N2b: More than or equal to 7 lymph node metastases	N2b: More than or equal to 7 lymph node metastases
M1: There is distant lymph node metastasis	M1: There is distant lymph node metastasis
M1a: Metastasis is limited to one organ or site (e.g., liver, lung, ovary, and extra-regional lymph node metastases)	M1a: Metastasis is limited to one organ or site (e.g., liver, lung, ovary, and extra-regional lymph node metastases)
M1b: Transfer more than one organ or site, or to the peritoneum1	M1b: Transfer more than one organ or site1
	M1c: Peritoneal metastases with or without metastasis of other organs1

¹Differences between the two versions.

Table 2 Colorectal cancer tumor-node-metastasis staging American Joint Committee on Cancer 7^th and 8^th editions

7th edition				8th edition
Stage	T	N	M	Stage	T	N	M
0	Tis	N0	M0	0	Tis	N0	M0
I	T1-2	N0	M0	I	T1-2	N0	M0
IIA	T3	N0	M0	IIA	T3	N0	M0
IIB	T4a	N0	M0	IIB	T4a	N0	M0
IIC	T4b	N0	M0	IIC	T4b	N0	M0
IIIA	T1-2	N1/N1c	M0	IIIA	T1-2	N1/N1c	M0
	T1	N2a	M0		T1	N2a	M0
IIIB	T3-4a	N1/N1c	M0	IIIB	T3-4a	N1/N1c	M0
	T2-3	N2a	M0		T2-3	N2a	M0
	T1-2	N2b	M0		T1-2	N2b	M0
IIIC	T4a	N2a	M0	IIIC	T4a	N2a	M0
	T3-4a	N2b	M0		T3-4a	N2b	M0
	T4b	N1-2	M0		T4b	N1-2	M0
IVA	Any T	Any N	M1a	IVA	Any T	Any N	M1a
IVB	Any T	Any N	M1b	IVB	Any T	Any N	M1b
				IVC	Any T	Any N	M1c

Table 3 American Joint Committee on Cancer 8^th edition updates for the colorectal cancer staging system

Update points	Update details	Level of evidence
Definition of distant transfer (M)	Introduction of M1c, specifically peritoneal metastasis, is an indicator of poor prognosis	I
Definition of regional lymph nodes (N)	Further introduce the definition of tumor deposit	II
Recommended additional indicators for guiding clinical practice	Lymphatic vessel infiltration: Reintroducing the meaning of L and V1 positive to correctly understand lymphatic and vascular invasion	I
Recommended additional indicators for guiding clinical practice	Microsatellite instability: Further explaining its importance as a prognostic risk and efficacy predictor	I
Recommended additional indicators for guiding clinical practice	Determine the KRAS, NRAS, and BRAF mutations as very important prognostic risk and efficacy predictors	I, II

¹L-positive infiltrates for medics and V-positive for venous infiltration.

Table 4 Two-way classification table of staging based on tumor-node-metastasis staging from AJCC-7^thvs tumor-node-metastasis staging from AJCC-8^th for patients with stages 0-IV colorectal cancer from 2006-2012 (n = 1090)

	TNM staging from AJCC-7th											Total
		0	I	IIA	IIB	IIC	IIIA	IIIB	IIIC	IVA	IVB
TNM staging from AJCC-8th	0	16	0	0	0	0	0	0	0	0	0	16
	I	0	131	0	0	0	0	0	0	0	0	131
	IIA	0	0	138	0	0	0	0	0	0	0	138
	IIB	0	0	0	56	0	0	0	0	0	0	56
	IIC	0	0	0	0	31	0	0	0	0	0	31
	IIIA	0	0	0	0	0	136	0	0	0	0	136
	IIIB	0	0	0	0	0	0	400	0	0	0	400
	IIIC	0	0	0	0	0	0	0	127	0	0	127
	IVA	0	0	0	0	0	0	0	0	24	0	24
	IVB	0	0	0	0	0	0	0	0	0	9	9
	IVC	0	0	0	0	0	0	0	0	0	22	22
		16	131	138	56	31	136	400	127	24	31	1090

TNM: Tumor-node-metastasis.

Table 5 Demographic and clinical characteristics of patients with stage 0-IV colorectal cancer from 2006-2012 (n, mean ± SD)

	N0	N1	N2	F or χ2	P
Gender				2.895	0.235
Male	242	182	126
Female	234	201	105
Age (yr)	62.46 ± 14.43	62.17 ± 14.43	61.98 ± 14.70	0.095	0.909
ASA				6.011	0.198
1	362	277	158
2	102	94	68
3	12	12	5
Primary site				4.94	0.895
Ileocecum	36	26	11
Right colon	43	30	22
Transverse colon	70	64	40
Left colon	88	72	46
Sigmoid colon	53	34	21
Rectum	186	157	91
Tumor size (cm)	3.31 ± 1.17	3.76 ± 0.82	4.11 ± 0.74	56.008	< 0.001
Operation method				8.233	0.411
RHC	97	67	43
LHC	186	154	91
HO	9	6	9
AR	145	112	70
APR	39	44	18
Operation time (m)	151.59 ± 36.31	156.40 ± 34.94	153.17 ± 31.30	2.044	0.130
Resection length (cm)	27.96 ± 9.92	27.26 ± 9.83	27.65 ± 9.92	0.533	0.587
Blood loss (mL)	184.39 ± 94.25	185.23 ± 95.26	194.30 ± 107.32	0.879	0.416
Tumor invasion				131.640	< 0.001
Tis	16	0	0
T1	85	17	9
T2	92	75	43
T3	162	127	132
T4a	82	108	22
T4b	39	56	25
Differentiation				188.64	< 0.001
Well	150	31	13
Moderate	276	296	124
Poor or undifferentiated	50	56	94
Number of LNs examined	14.70 ± 1.88	14.13 ± 1.78	14.26 ± 1.85	0.408	0.665
Number of positive LNs	0	1.85 ± 0.73	5.46 ± 1.64	3050.47	< 0.001
Complication				4.088	0.130
No	436	349	201
Yes	40	34	30
Chemotherapy				295.36	< 0.001
Yes	283	383	229
No	193	0	2
TNM staging AJCC-7th				887.08	< 0.001
0	16	0	0
I	131	0	0
IIA	138	0	0
IIB	56	0	0
IIC	31	0	0
IIIA	45	82	9
IIIB	49	234	117
IIIC	9	47	71
IVA	1	15	8
IVB	0	5	26
TNM staging AJCC-8th				887.32	< 0.001
0	16	0	0
I	131	0	0
IIA	138	0	0
IIB	56	0	0
IIC	31	0	0
IIIA	45	82	9
IIIB	49	234	117
IIIC	9	47	71
IVA	1	15	8
IVB	0	1	8
IVC	0	4	18

TNM: Tumor-node-metastasis.

Table 6 Comparison of 5-year disease-free survival and overall survival rate for stage and sub-stage using American Joint Committee on Cancer-7^th edition and American Joint Committee on Cancer-8^th edition (%)

			0	I	IIA	IIB	IIC	IIIA	IIIB	IIIC	IVA	IVB	IVC	Log-rank χ2	P
OS	Sub-stage	AJCC-7	100	98.5	82.6	76.8	67.7	65.4	60	44.9	8.3	0	-	1423.53	< 0.01
		AJCC-8	100	98.5	82.6	76.8	67.7	65.4	60	44.9	8.3	0	0	1608.11	< 0.01
					II			III			IV
	Stage	AJCC-7	100	98.5	79.1			58.2			3.6			913.56	< 0.01
		AJCC-8	100	98.5	79.1			58.2			3.6			875.46
DFS	Sub-stage	AJCC-7	100	93.1	78.3	73.2	61.3	65.4	56.3	37	8.3	0	-	1418.9	< 0.01
		AJCC-8		93.1	78.3	73.2	61.3	65.4	56.3	37	8.3	0	0	1603.4	< 0.01
					II			III			IV
	Stage	AJCC-7	100	93.1	74.7			54.4			3.6			875.46	< 0.01
		AJCC-8		93.1	74.7			54.4			3.6			875.46	< 0.01

DFS: Disease-free survival; OS: Overall survival; AJCC: American Joint Committee on Cancer.