Colorectal Cancer Health Center

Note: The American Joint Committee on Cancer (AJCC) has recently published a new edition of the AJCC Cancer Staging Manual, which includes revisions to the staging for this disease. The PDQ Adult Treatment Editorial Board, which is responsible for maintaining this summary, is currently reviewing the new staging to determine the changes that need to be made in the summary. In addition to updating this Stage Information section, additional changes may need to be made to other parts of this summary to ensure that it is up-to-date. The changes will be made as soon as possible.

The anal canal extends from the rectum to the perianal skin and is lined by a mucous membrane that covers the internal sphincter. The following is a staging system for anal canal cancer that has been described by the AJCC and the International Union Against Cancer.[1] Tumors of the anal margin (below the anal verge and involving the perianal hair-bearing skin) are classified with skin tumors.

TNM Definitions

Primary tumor (T)

• TX: Primary tumor cannot be assessed
• T0: No evidence of primary tumor
• Tis: Carcinoma in situ
• T1: Tumor 2 cm or less in greatest dimension
• T2: Tumor more than 2 cm but not more than 5 cm in greatest dimension
• T3: Tumor more than 5 cm in greatest dimension
• T4: Tumor of any size that invades adjacent organ(s), e.g., vagina, urethra, bladder*

*Direct invasion of the rectal wall, perirectal skin, subcutaneous tissue, or the sphincter muscle(s) is not classified as T4.

Regional lymph nodes (N)

• NX: Regional lymph nodes cannot be assessed
• N0: No regional lymph node metastasis
• N1: Metastasis in perirectal lymph node(s)
• N2: Metastasis in unilateral internal iliac and/or inguinal lymph node(s)
• N3: Metastasis in perirectal and inguinal lymph nodes and/or bilateral internal iliac and/or inguinal lymph nodes

Distant metastasis (M)

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

AJCC Stage Groupings

Stage 0

• Tis, N0, M0

Stage I

• T1, N0, M0

Stage II

• T2, N0, M0
• T3, N0, M0

Stage IIIA

• T1, N1, M0
• T2, N1, M0
• T3, N1, M0
• T4, N0, M0

Stage IIIB

• T4, N1, M0
• Any T, N2, M0
• Any T, N3, M0

Stage IV

• Any T, any N, M1

References:

1. Anal canal. In: American Joint Committee on Cancer.: AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer, 2002, pp 125-130.