Anus and perianal area

Author: Nat Pernick, M.D. (see Authors page)

Revised: 19 October 2017, last major update April 2005

Copyright: (c) 2002-2017,, Inc.

PubMed Search: Anus staging [title]

Cite this page: Pernick, N. Staging. website. Accessed February 21st, 2018.
Definition / general
  • No changes from AJCC sixth edition to AJCC seventh edition
  • This staging system applies to anal canal tumors but excludes perianal tumors, melanoma, carcinoid tumors and sarcoma
  • Use skin staging system for perianal tumors (arise from skin or distal to squamous mucocutaneous junction)
  • Anal canal tumors now tend to be staged clinically, as treatment is often nonsurgical
  • However, treatment of perianal carcinomas is primarily surgical
  • Stage tumors overlapping the anorectal junction as anal tumors if epicenter is distal to or 2 cm or less proximal from dentate line and as rectal tumors if epicenter is more than 2 cm proximal to dentate line
Primary tumor (T)
TX: Primary tumor cannot be assessed
T0: No evidence of primary tumor
Tis: Carcinoma in situ (Bowen disease, high grade squamous intraepithelial lesion / HSIL, anal intraepithelial neoplasia / AIN II - III)
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): vagina, urethra, bladder

  • Note: direct invasion of the rectal wall, perirectal skin, subcutaneous tissue or sphincter muscle is not classified as pT4
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 or inguinal lymph node(s)
N3: Metastasis in perirectal and inguinal lymph nodes or bilateral internal iliac or inguinal lymph nodes

  • Regional lymph nodes: perirectal (anorectal, perirectal, lateral sacral), internal iliac (hypogastric), inguinal (superficial)
Isolated tumor cells (ITC) - not part of TNM
  • ITC are single cells or small clusters of cells 0.2 mm or less, found by routine H&E, immunohistochemistry, PCR or other
  • Lymph nodes or distant sites with ITC are classified as pN0 or pM0

pN0 (i+): ITC detectable by any morphologic method but not histologically
pN0 (i-): ITC not detectable by any morphologic method or histologically
pN0 (mol+): ITC detectable by any molecular method but not histologically
pN0 (mol-): ITC detectable by any molecular method or histologically
Distant metastases
M0: No distant metastasis
M1: Distant metastasis
Stage grouping and 5 year survival (squamous, nonsquamous)
Stage 0: Tis N0 M0
Stage I: T1 N0 M0 (71.4%, 59.1%)
Stage II: T2 - T3 N0 M0 (63.5%, 52.9%)
Stage IIIA: T1 - T3 N1 M0 or T4 N0 M0 (48.1%, 37.7%)
Stage IIIB: T4 N1 M0 or Any T N2 - N3 M0 (43.2%, 24.4%)
Stage IV: Any T, Any N, M1 (20.9%, 7.4%)
Alternative staging
A: Intraepithelial or superficially invasive
B: Penetrate into muscularis propria or adjacent pelvic tissue
C: Regional nodal metastases
D: Massive local spread or distant metastases; unresectable