TNM Definitions
AJCC Stage Groupings

Treatment decisions should be made with reference to the TNM classification,[1] rather than the older Dukes or the Modified Astler-Coller (MAC) classification schema.

The American Joint Committee on Cancer and a National Cancer Institute-sponsored panel recommended that at least 12 lymph nodes be examined in patients with colon and rectal cancer to confirm the absence of nodal involvement by tumor.[1-3] This recommendation takes into consideration that the number of lymph nodes examined is a reflection of both the aggressiveness of lymphovascular mesenteric dissection at the time of surgical resection and the pathologic identification of nodes in the specimen. Retrospective studies INT-0089 demonstrated that the number of lymph nodes examined in colon and rectal surgery may be associated with patient outcome.[4-7]

The AJCC has designated staging by TNM classification.[1]

Primary tumor (T)

• TX: Primary tumor cannot be assessed
• T0: No evidence of primary tumor
• Tis: Carcinoma in situ: intraepithelial or invasion of the 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 the visceral peritoneum**,***

* [Note: Tis includes cancer cells confined within the glandular basement membrane (intraepithelial) or lamina propria (intramucosal) with no extension through the muscularis mucosae into the submucosa.]

** [Note: 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.]

*** [Note: 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.]

Regional lymph nodes (N)

• 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

 [Note: 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 is represents venous invasion.]

Distant metastasis (M)

• MX: Distant metastasis cannot be assessed
• M0: No distant metastasis
• M1: Distant metastasis

Stage 0

• Tis, N0, M0

Stage I

• T1, N0, M0
• T2, N0, M0

Stage IIA

• T3, N0, M0

Stage IIB

• T4, N0, M0

Stage IIIA

• T1, N1, M0
• T2, N1, M0

Stage IIIB

• T3, N1, M0
• T4, N1, M0

Stage IIIC

• Any T, N2, M0

Stage IV

• Any T, any N, M1

References

1. Colon and rectum. In: American Joint Committee on Cancer.: AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer, 2002, pp 113-124. 
   
   
2. Compton CC, Greene FL: The staging of colorectal cancer: 2004 and beyond. CA Cancer J Clin 54 (6): 295-308, 2004 Nov-Dec.  [PUBMED Abstract]
   
   
3. Nelson H, Petrelli N, Carlin A, et al.: Guidelines 2000 for colon and rectal cancer surgery. J Natl Cancer Inst 93 (8): 583-96, 2001.  [PUBMED Abstract]
   
   
4. Swanson RS, Compton CC, Stewart AK, et al.: The prognosis of T3N0 colon cancer is dependent on the number of lymph nodes examined. Ann Surg Oncol 10 (1): 65-71, 2003 Jan-Feb.  [PUBMED Abstract]
   
   
5. Le Voyer TE, Sigurdson ER, Hanlon AL, et al.: Colon cancer survival is associated with increasing number of lymph nodes analyzed: a secondary survey of intergroup trial INT-0089. J Clin Oncol 21 (15): 2912-9, 2003.  [PUBMED Abstract]
   
   
6. Prandi M, Lionetto R, Bini A, et al.: Prognostic evaluation of stage B colon cancer patients is improved by an adequate lymphadenectomy: results of a secondary analysis of a large scale adjuvant trial. Ann Surg 235 (4): 458-63, 2002.  [PUBMED Abstract]
   
   
7. Tepper JE, O'Connell MJ, Niedzwiecki D, et al.: Impact of number of nodes retrieved on outcome in patients with rectal cancer. J Clin Oncol 19 (1): 157-63, 2001.  [PUBMED Abstract]
   
   

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