TNM Definitions
AJCC Stage Groupings

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

The American Joint Committee on Cancer (AJCC) 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 the aggressiveness of lymphovascular mesenteric dissection at the time of surgical resection and the pathologic identification of nodes in the specimen. Retrospective studies 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 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 macroscopically to other organs or structures is classified T4. If no tumor is present in the adhesion microscopically, however, 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 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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