Table 1.
American Joint Committee on Cancer TNM Staging System for Colorectal Cancer*
| Primary Tumor (T) | |||||
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| 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 subserosa or into nonperitonealized pericolic or perirectal tissues | ||||
| T4 | Tumor directly invades other organs or structures and/or perforates visceral peritoneum‡ | ||||
| Regional Lymph Nodes (N) § | |||||
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| NX | Regional lymph nodes cannot be assessed | ||||
| N0 | No regional lymph node metastasis | ||||
| N1 | Metastasis in one to three regional lymph nodes | ||||
| N2 | Metastasis in four or more regional lymph nodes | ||||
| Distant Metastasis (M) | |||||
|
| |||||
| MX | Distant metastasis cannot be assessed | ||||
| M0 | No distant metastasis | ||||
| M1 | Distant metastasis | ||||
| Stage Grouping | |||||
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| |||||
| Stage | T | N | M | Dukes¶ | MAC¶ |
| 0 | Tis | N0 | M0 | – | – |
| 1 | T1 | N0 | M0 | A | A |
| T2 | N0 | M0 | A | B1 | |
| IIA | T3 | N0 | M0 | B | B2 |
| IIB | T4 | N0 | M0 | B | B3 |
| IIIA | T1-T2 | N1 | M0 | C | C1 |
| IIIB | T3-T4 | N1 | M0 | C | C2/C3 |
| IIIC | Any T | N2 | M0 | C | C1/C2/C3 |
| IV | Any T | Any N | M1 | – | D |
| Histologic Grade (G) | |||||
|
| |||||
| GX | Grade cannot be assessed | ||||
| G1 | Well differentiated | ||||
| G2 | Moderately differentiated | ||||
| G3 | Poorly differentiated | ||||
| G4 | Undifferentiated | ||||
This includes cancer cells confined within the glandular basement membrane (intraepithelial) or lamina propria (intramucosal) with no extension through the muscularis mucosae into the submucosa.
Direct invasion in T4 includes invasion of other segments of the colorectum by way of the serosa, for example, invasion of the sigmoid colon by a carcinoma of the cecum. Tumor that is adherent to other organs or structures macroscopically is classified T4; however, if no tumor is present in the adhesion microscopically the classification should be pT3. The V and L substaging should be used to identify the presence or absence of vascular or lymphatic invasion.
A tumor nodule in the pericolorectal adipose tissue of a primary carcinoma without histologic evidence of residual lymph node in the nodule is classified in the pN category as a regional lymph node metastasis if the nodule has the form and smooth contour of a lymph node. If the nodule has an irregular contour, it should be classified in the T category and also coded as V1 (microscopic venous invasion) or as V2 (if it was grossly evident) because there is a strong likelihood that it represents venous invasion.
Dukes B is a composite of better (T3 N0 M0) and worse (T4 N0 M0) prognostic groups, as is Dukes C (Any TN1 M0 and Any T N2 M0). MAC is the modified Astler-Coller classification.
Note: The y prefix is to be used for those cancers that are classified after pretreatment, whereas the r prefix is to be used for those cancers that have recurred.
Used with the permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original source for this material is the AJCC Cancer Staging Manual, 6th Edition (2002), published by Springer-Verlag New York (www.springer-ny.com).