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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 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.[2,3,4] 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.[5,6,7,8]
Definitions of TNM
The AJCC has designated staging by TNM classification to define colon cancer.[1] The same classification is used for both clinical and pathologic staging.[1]
Table 1. Primary Tumora
| TX | Primary tumor cannot be assessed. |
| T0 | No evidence of primary tumor. |
| Tis | Carcinoma in situ: intraepithelial or invasion of lamina propria.b |
| T1 | Tumor invades submucosa. |
| T2 | Tumor invades muscularis propria. |
| T3 | Tumor invades through the muscularis propria into pericolorectal tissues. |
| T4a | Tumor penetrates to the surface of the visceral peritoneum.c |
| T4b | Tumor directly invades or is adherent to other organs or structures.c, d |
Table 2. Regional Lymph Nodes (N)a,b
| NX | Regional lymph nodes cannot be assessed. |
| N0 | No regional lymph node metastasis. |
| N1 | Metastases in 1–3 regional lymph nodes. |
| N1a | Metastasis in 1 regional lymph node. |
| N1b | Metastases 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 | Metastases in =4 regional lymph nodes. |
| N2a | Metastases in 4–6 regional lymph nodes. |
| N2b | Metastases in =7 regional lymph nodes. |
Table 3. Distant Metastasis (M)a
| M0 | No distant metastasis. |
| M1 | Distant metastasis. |
| M1a | Metastasis confined to 1 organ or site (e.g., liver, lung, ovary, nonregional node). |
| M1b | Metastases in >1 organ/site or the peritoneum. |
Table 4. Anatomic Stage/Prognostic Groupsa,b
| Stage | T | N | M | Dukesc | MACc |
| 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 | – | – |
References:
Purpose of This Summary
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the treatment of colon cancer. It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.
Reviewers and Updates
This summary is reviewed regularly and updated as necessary by the PDQ Adult Treatment Editorial Board. Board members review recently published articles each month to determine whether an article should:
Changes to the summaries are made through a consensus process in which Board members evaluate the strength of the evidence in the published articles and determine how the article should be included in the summary.
The lead reviewers for Colon Cancer Treatment are:
Any comments or questions about the summary content should be submitted to Cancer.gov through the Web site's Contact Form. Do not contact the individual Board Members with questions or comments about the summaries. Board members will not respond to individual inquiries.
Levels of Evidence
Some of the reference citations in this summary are accompanied by a level-of-evidence designation. These designations are intended to help readers assess the strength of the evidence supporting the use of specific interventions or approaches. The PDQ Adult Treatment Editorial Board uses a formal evidence ranking system in developing its level-of-evidence designations.
Permission to Use This Summary
PDQ is a registered trademark. Although the content of PDQ documents can be used freely as text, it cannot be identified as an NCI PDQ cancer information summary unless it is presented in its entirety and is regularly updated. However, an author would be permitted to write a sentence such as "NCI's PDQ cancer information summary about breast cancer prevention states the risks succinctly: [include excerpt from the summary]."
The preferred citation for this PDQ summary is:
National Cancer Institute: PDQ® Colon Cancer Treatment. Bethesda, MD: National Cancer Institute. Date last modified <MM/DD/YYYY>. Available at: http://cancer.gov/cancertopics/pdq/treatment/colon/HealthProfessional. Accessed <MM/DD/YYYY>.
Images in this summary are used with permission of the author(s), artist, and/or publisher for use within the PDQ summaries only. Permission to use images outside the context of PDQ information must be obtained from the owner(s) and cannot be granted by the National Cancer Institute. Information about using the illustrations in this summary, along with many other cancer-related images, is available in Visuals Online, a collection of over 2,000 scientific images.
Disclaimer
Based on the strength of the available evidence, treatment options may be described as either "standard" or "under clinical evaluation." These classifications should not be used as a basis for insurance reimbursement determinations. More information on insurance coverage is available on Cancer.gov on the Coping with Cancer: Financial, Insurance, and Legal Information page.
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Last Revised: 2011-04-13
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