Colorectal cancer (TNM staging 7th edition)

Last revised by Yuranga Weerakkody on 9 Jan 2023

The 7th edition of the TNM classification of colorectal carcinomas was proposed in 2010, and has now been updated and replaced by the 8th edition, published in 2016.

  • Tx: primary tumor cannot be assessed

  • T0: no evidence of primary tumor

  • Tis: carcinoma in situ

  • T1: into (but not through) submucosa

  • T2: into (but not through) muscularis propria

  • T3

    • through muscularis propria into subserosa, or

    • into non-peritonealised pericolic/perirectal tissues

  • T4a: penetration of the visceral peritoneal layer

  • T4b: penetration or adhesion to adjacent organs

  • Nx: nodes cannot be assessed

  • N0: no evidence of nodal involvement

  • N1a: involvement of one regional node

  • N1b: involvement of 2-3 regional nodes

  • N1c: deposits involving serosa or non-peritonealised pericolic/perirectal tissues without regional nodal metastasis

  • N2a: involvement of 4-6 nodes

  • N2b: involvement of ≥7 nodes

  • Mx: presence of metastases cannot be assessed

  • M0: no evidence of metastases

  • M1a: distant metastases confined to one organ (e.g. liver, lung, ovary, non-regional node)

  • M1b: distant metastases confined to more than one organ or to the peritoneum

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