Colon Cancer Staging 

Updated: Jan 04, 2017
  • Author: Lewis J Rose, MD; Chief Editor: N Joseph Espat, MD, MS, FACS  more...
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TNM Classification for Colon Cancer

The American Joint Committee on Cancer (AJCC) tumor/node/metastasis (TNM) classification and staging system for colon cancer are provided below. [1, 2]

See Benign or Malignant: Can You Identify These Colonic Lesions?, a Critical Images slideshow, to help identify the features of benign lesions as well as those with malignant potential.

Table. TNM Classification for Colon Cancer (Open Table in a new window)

Primary tumor (T)
TX Primary tumor cannot be assessed
T0 No evidence of primary tumor
Tis Carcinoma in situ: intraepithelial or invasion of lamina propria
T1 Tumor invades submucosa
T2 Tumor invades muscularis propria
T3 Tumor invades through the muscularis propria into the pericolorectal tissues
T4a Tumor penetrates to the surface of the visceral peritoneum
T4b Tumor directly invades or is adherent to other organs or structures
Regional lymph nodes (N)
NX Regional lymph nodes cannot be assessed
N0 No regional lymph node metastasis
N1 Metastasis in 1-3 regional lymph nodes
N1a Metastasis in 1 regional lymph node
N1b Metastasis in 2-3 regional lymph nodes
N1c Tumor deposit(s) in the subserosa, mesentery, or nonperitonealized pericolic or perirectal tissues without regional nodal metastasis
N2 Metastasis in 4 or more lymph nodes
N2a Metastasis in 4-6 regional lymph nodes
N2b Metastasis in 7 or more regional lymph nodes
Distant metastasis (M)
M0 No distant metastasis
M1 Distant metastasis
M1a Metastasis confined to 1 organ or site (eg, liver, lung, ovary, nonregional node)
M1b Metastases in more than 1 organ/site or the peritoneum

Table. Anatomic stage/prognostic groups (Open Table in a new window)

Stage T N M Dukes MAC
0 Tis N0 M0 -- --
I T1 N0 M0 A A
  T2 N0 M0 A B1
IIA T3 N0 M0 B B2
IIB T4a N0 M0 B B2
IIC T4b N0 M0 B B3
IIIA T1-T2 N1/N1c M0 C C1
  T1 N2a M0 C C1
IIIB T3-T4a N1/N1c M0 C C2
  T2-T3 N2a M0 C C1/C2
  T1-T2 N2b M0 C C1
IIIC T4a N2a M0 C C2
  T3-T4a N2b M0 C C2
  T4b N1-N2 M0 C C3
IVA Any T Any N M1a -- --
IVB Any T Any N M1b -- --

Staging information

Features of revised staging give more importance to the poor prognostic features of depth of invasion in spite of less positive nodes.

  • T4 is divided between penetration to surface of visceral peritoneum and direct gross adherence to adjacent structures
  • T1-2N2 is downstaged from stage IIIC to IIIA or IIIB, depending on the number of nodes involved
  • Shift T4bN1 from IIIB to IIIC
  • Subdivide T4/N1/N2
  • Resolution of staging for issue of mesenteric deposits where nodal tissue is not identified
  • Revised substaging of stage II based on depth of invasion, with addition of stage IIC
  • Revised substaging of stage III based on node number (N1a—1 node; N1b—2-3 nodes; N2a—4-6 nodes; N2b—7 or more nodes)
  • Division of metastases to 1 or more sites in recognition of possibility of curative approach for aggressive treatment of single site of metastatic disease