Table 2

Summary of TNM/pTNM categories from the last 3 editions of the UICC pTNM system for colorectal carcinoma and the corresponding disease stages14,16,17,19,20

TNM/pTNM categories4th edition145–6th editions (modifications)16,17,19,20
Tx/pTxPrimary tumour cannot be assessed
T0/pT0No evidence of primary tumour
Tis/pTisCarcinoma in situCarcinoma in situ (intraepithelial or intramucosal, with invasion of lamina propria)
T1/pT1Tumour invades submucosa
T2/pT2Tumour invades muscularis propria
T3/pT3Tumour invades through muscularis propria into subserosa or into non-peritonealised pericolic or perirectal tissues
T4/pT4Tumour directly invades other organs or structures and/or perforates visceral peritoneum*
Nx/pNxRegional LNs cannot be assessed
N0/pN0No regional LN metastasis
N1/pN1Metastasis to 1–3 pericolic or perirectal LNsMetastasis to 1–3 regional LNs
N2/pN2Metastasis to 4 or more pericolic or perirectal LNsMetastasis to 4 or more regional LNs
N3/pN3Metastasis to LNs along the course of a named vascular trunkNo N3/pN3 category
Mx/pMxDistant metastasis cannot be assessed
M0/pM0No distant metastasis
M1/pM1Distant metastasis
Disease stages4th edition145th edition19,206th edition16,17
*Adherence to other structures or organs must be proved by histology for a pT4 classification: a grossly adherent tumour with no microscopic evidence of adherence is T4, but pT3.
LN, lymph node.
Stage 0Tis N0 M0Tis N0 M0Tis N0 M0
Stage IT1–T2 N0 M0T1–T2 N0 M0T1–T2 N0 M0
Stage IIT3–T4 N0 M0T3–T4 N0 M0Stage IIA: T3 N0 M0
Stage IIB: T4 N0 M0
Stage IIIAny T N1–N3 M0Any T N1–N2 M0Stage IIIA: T1–T2 N1 M0
Stage IIIB: T3–T4 N1 M0
Stage IIIC: any T N2 M0
Stage IVAny T any N M1Any T any N M1Any T any N M1