Up until fairly recently, we used to stage anal margin cancers (cancers up to 5cm away from the anal margin) differently to anal canal tumours, The rationale for this was that anal margin cancer were associated with a better prognosis, perhaps because they were more readily excised without risking sphincter function and also perhaps as patients more likely to notice the lesion sooner.
This has changed in the most recent edition of the American Joint Committee TMN Staging where the two staging classifications have been merged together for better clarity. The most recent classification is given below.
Although this is based on the previous staging classification, the 5 year survival associated with each clinical stage is as follows: Stage 1 86%, Stage 2: 77%, Stage 3: 66%, Stage 4: 37%.
The literature suggests that approximately half of patients present with Stage 1 or Stage 2 disease.
American Joint Committee on Cancer recommended TMN staging 8th Edition of Anal Squamous Cell Carcinomas of Anal margin and Anal Canal.
| TMN Anal Squamous Cell Carcinomas: Combined Anal Canal and Anal Margin (within 5cm) | |||||
| T1 | Tumour less than 2 cm | N0 | No regional lymph nodes | M0 | No distant metastases |
| T2 | Tumour less than 5 cm but greater than 2cm | N1a | Metastases in inguinal, mesorectal and/or internal iliac lymph nodes | M1 | Distant Metastases |
| T3 | Tumour greater than 5 cm | N1b | Metastases in external iliac lymph nodes | ||
| T4 | Tumour of any size that invades adjacent organs | N1c | Metastases in external iliac and in inguinal, mesorectal and/or internal iliac lymph nodes | ||
Classification of TMN staging 8th Edition for Anal Squamous Cell Carcinomas.
| Classificationof staging | |||
| Stage I | T1 | N0 | M0 |
| Stage IIA | T2 | N0 | M0 |
| Stage IIB | T3 | N0 | M0 |
| Stage IIIA | T1/T2 | N1 | M0 |
| Stage IIIB | T4 | N0 | M0 |
| Stage IIIC | T3/T4 | N1 | M0 |
| Stage IV | Any T | Any N | M1 |