Table 2.

TNM staging system for colon cancer[57]

	Tumour stage (T)	Nodal stage (N)	Metastasis (M)
X	Primary tumour can not be assessed	Nodal metastasis can not be assessed	Distant metastasis can not be assessed
0	No primary tumor identified	No nodal metastasis	No distant metastases
is	Carcinoma in situ (tumour limited to mucosa
1	Involvement of submucosa, but no penetration through muscularis propria	1-3 pericolic/ perirectal nodes involved.	Distant metastases
2	Invasion into, but not penetration through, muscularis propria	4 or more pericolic/ perirectal nodes involved
3	Penetration through muscularis propria in o subserosa (if present), or pericolic fat, but not into peritoneal cavity or other organs.
4	Invasion of other organs or involvement of free peritoneal cavity