Table 1.

Stage systems AJCC, Dukes, and Astler-Coller. AJCC system is the most used and precise staging system for CRC and combines three letters (T: for the primary tumour, N: for spread to lymph nodes, and M: for metastasis) and numbers from 0 to 4 (indicating more severity for a higher number).

AJCC/TNM		Dukes	Astler-Coller
Stage 0	Tis, N0, M0	—	—
Stage I	T1-T2, N0, M0	A	A, B1
Stage IIA	T3, N0, M0	B	B2
Stage IIB	T4a, N0, M0	B	B2
Stage IIC	T4b, N0, M0	B	B3
Stage IIIA	T1-T2, N1, M0	C	C1
	T1, N2a, M0
Stage IIIB	T3-T4a, N1, M0	C	C1, C2
	T2-T3, N2a, M0
	T1-T2, N2b, M0
Stage IIIC	T4a, N2a, M0	C	C2, C3
	T3-T4, N2b, M0
	T4b, N1-N2, M0
Stage IV	Any T, Any N, M1a	—	D
	Any T, Any N, M1b