Colorectal cancer (staging)

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Colorectal carcinoma staging can be performed using two systems. The traditional Dukes staging system has largely been replaced by the TNM system but is nonetheless often used clinically.

Staging

Dukes (Astler-Coller modification)
  • stage A: confined to mucosa
  • stage B: through muscularis propria
  • stage C: local lymph node involvement
  • stage D: distant metastases
TNM staging
Primary tumor staging (T)
  • 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
Nodal status (N)
  • Nx: nodes cannot be assessed
  • N0: no evidence of nodal involvement
  • N1a: involvement of one regional nodes
  • 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
Metastases (M)
  • 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