Stage Information for Rectal Cancer
Treatment decisions should be made with reference to the TNM classification system, rather than 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 the tumor.[2,3,4] 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, such as Intergroup trial INT-0089 , have demonstrated that the number of lymph nodes examined in colon and rectal surgery may be associated with patient outcome.[5,6,7,8]
The staging system does not apply to the following histologies:
- Sarcoma. (See the PDQ summary on Adult Soft Tissue Sarcoma Treatment for more information.)
- Lymphoma. (See the PDQ summary on Adult Hodgkin Lymphoma Treatment for more information.)
- Carcinoid tumors. (See the PDQ summary on Gastrointestinal Carcinoid Tumors Treatment for more information.)
- Melanoma. (See the PDQ summary on Melanoma Treatment for more information.)
Definitions of TNM
The AJCC has designated staging by TNM classification to define rectal cancer. The same classification is used for both clinical and pathologic staging.
Table 1. Primary Tumora
a Reprinted with permission from AJCC: Colon and rectum. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 143-164.
b Tis includes cancer cells confined within the glandular basement membrane (intraepithelial) or mucosal lamina propria (intramucosal) with no extension through the muscularis mucosae into the submucosa.
c Direct invasion in T4 includes invasion of other organs or other segments of the colorectum as a result of direct extension through the serosa, as confirmed on microscopic examination (e.g., invasion of the sigmoid colon by a carcinoma of the cecum) or, for cancers in a retroperitoneal or subperitoneal location, direct invasion of other organs or structures by virtue of extension beyond the muscularis propria (i.e., respectively, a tumor on the posterior wall of the descending colon invading the left kidney or lateral abdominal wall; or a mid or distal rectal cancer with invasion of prostate, seminal vesicles, cervix, or vagina).
d Tumor that is adherent to other organs or structures, grossly, is classified cT4b. However, if no tumor is present in the adhesion, microscopically, the classification should be pT1-4a depending on the anatomical depth of wall invasion. The V and L classifications should be used to identify the presence or absence of vascular or lymphatic invasion, whereas the PN site-specific factor should be used for perineural invasion.
|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.cd|