Anal Canal and Perianal Skin
77
Anal Canal and Perianal Skin (ICD‐O‐3 C21, ICD‐O‐3 C44.5) The anal canal extends from rectum to perianal skin (to the junction with hair‐bearing skin). It is lined by the mucous membrane overlying the internal sphincter, including the transitional epithelium and dentate line. Tumours of anal margin and perianal skin defined as within 5 cm of the anal margin (ICD‐O C44.5) are now classified with carcinomas of the anal canal.
The classification applies only to carcinomas. There should be histological confirmation of the disease and division of cases by histological type. The following are the procedures for assessing T, N, and M categories. T categories Physical examination, imaging, endoscopy, and/or surgical exploration N categories Physical examination, imaging, and/or surgical exploration M categories Physical examination, imaging, and/or surgical exploration
Regional Lymph Nodes The regional lymph nodes are the perirectal, the internal iliac, external iliac, and the inguinal lymph nodes.
TNM Clinical Classification T – Primary Tumour TX Primary tumour cannot be assessed T0 No evidence of primary tumour Tis Carcinoma in situ, Bowen disease, high‐grade squamous intraepithelial lesion (HSIL), anal intraepithelial neoplasia II–III (AIN II–III)
T1 Tumour 2 cm or less in greatest dimension T2 Tumour more than 2 cm but not more than 5 cm in greatest dimension T3 Tumour more than 5 cm in greatest dimension T4 Tumour of any size invades adjacent organ(s), e.g., vagina, urethra, bladder*
Digestive System
Rules for Classification
78
Digestive System Tumours
Note * Direct invasion of the rectal wall, perianal skin, subcutaneous tissue, or the sphinc ter muscle(s) alone is not classified as T4.
N – Regional Lymph Nodes NX Regional lymph nodes cannot be assessed N0 No regional lymph node metastasis N1 Metastasis in regional lymph node(s) N1a Metastases in inguinal, mesorectal, and/or internal iliac nodes N1b Metastases in external iliac nodes N1c Metastases in external iliac and in inguinal, mesorectal and/or internal iliac nodes
M – Distant Metastasis M0 No distant metastasis M1 Distant metastasis
pTNM Pathological Classification The pT and pN categories correspond to the T and N categories. For pM see page 8. pN0 Histological examination of a regional perirectal/pelvic lymphad enectomy specimen will ordinarily include 12 or more lymph nodes; histological examination of an inguinal lymphadenectomy specimen will ordinarily include 6 or more lymph nodes. If the lymph nodes are negative, but the number ordinarily examined is not met, classify as pN0.
Stage Stage 0 Stage I Stage IIA Stage IIB Stage IIIA Stage IIIB Stage IIIC Stage IV
Tis T1 T2 T3 T1, T2, T4 T3,T4 Any T
N0 N0 N0 N0 N1 N0 N1 Any N
M0 M0 M0 M0 M0 M0 M0 M1
Anal Canal and Perianal Skin
79
Prognostic Factors Grid – Anal Canal Prognostic Tumour related factors
Host related
Environment related
Essential
T, N and M category
Age Male gender
Cigarette smoking Social deprivation
Additional
Skin ulceration Sphincter involvement Primary tumour size >5 cm
Immune suppression Long‐term corticosteroids HIV
New and promising
Squamous cell carcinoma antigen (SCCAg)
Concomitant herpes simplex virus (HSV) Haemoglobin level
Source: UICC Manual of Clinical Oncology, Ninth Edition. Edited by Brian O’Sullivan, James D. Brierley, Anil K. D’Cruz, Martin F. Fey, Raphael Pollock, Jan B. Vermorken and Shao Hui Huang. © 2015 UICC. Published 2015 by John Wiley & Sons, Ltd.
Digestive System
Prognostic factors for outcome in anal cancer