Pathologic Assessment of Rectal Carcinoma after Neoadjuvant Radio(chemo)therapy: Prognostic Implications

Table 2

Major changes in the last 4 editions of TNM classification for colorectal cancer.

Edition (year)	T category	N category	M category	Stage grouping
4th (1987)	—	Introducing N3 category	—	—
5th (1997)	—	Removing N3 category	—	—
	TDs: introducing the 3 mm rule			—
6th (2002)	TDs: replacing the 3 mm rule with the contour rule		—	Subdividing stage III into IIIA, IIIB, and IIIC
	T4 split into T4a and T4b	ITC considered as N0
7th (2009)	Changes in TD classification		M1 split into M1a and M1b	Subdividing stage IV into IVA and IVB
	—	Subdividing N1 into N1a, N1b, and N1c and N2 into N2a and N2b

ITC, isolated tumour cells.