Anal Cancer Staging 

Updated: Oct 22, 2021
Author: Kirby Rebecca Walker, MD; Chief Editor: N Joseph Espat, MD, MS, FACS 

TNM Classification for Anal Cancer

The American Joint Committee on Cancer (AJCC) tumor/node/metastasis (TNM) classification and staging system for anal cancer are provided below.[1, 2, 3]

Table 1. TNM Classification for Anal Cancer (Open Table in a new window)

Primary tumor (T)

TX

Primary tumor cannot be assessed

T0

No evidence of primary tumor

Tis

High-grade squamous intraepithelial lesion (previously termed carcinoma in situ, Bowen disease, anal intraepithelial neoplasia II–III, high-grade anal intraepithelial neoplasia)

T1

Tumor ​≤ 2 cm in greatest dimension

T2

Tumor > 2 cm but ≤ 5 cm in greatest dimension

T3

Tumor > 5 cm in greatest dimension

T4

Tumor of any size invades adjacent organ(s) (eg, vagina, urethra, bladder)

Regional lymph nodes (N)

NX

Regional lymph nodes cannot be assessed

N0

No regional lymph node metastasis

N1

Metastasis in inguinal, mesorectal, internal iliac, or external iliac nodes

  N1a - Metastasis in inguinal, mesorectal, or internal iliac lymph nodes

  N1b - Metastasis in external iliac lymph nodes

  N1c - Metastasis in external iliac with any N1a nodes

Distant metastasis (M)

M0

No distant metastasis

M1

Distant metastasis

Table 2. Anatomic stage/prognostic group (Open Table in a new window)

Stage

T

N

M

0

Tis

N0

M0

I

T1

N0

M0

IIA

T2

N0

M0

IIB

T3

N0

M0

IIIA

T1-T2

N1

M0

IIIB

T4

N0

M0

IIIC

T3-T4

N1

M0

IV

Any T

Any N

M1

 

Table 3. Histologic Grade (Open Table in a new window)

Grade  Definition 
GX

Grade cannot be determined 

G1  Well differentiated (low grade)
G2 Moderately differentiated (low grade) 
G3 Poorly differentiated (high grade)
G4 Undifferentiated (high grade)

 

 

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