Diagnosis & staging
These are tests that may be used to diagnose this type of cancer.
- Physical examination
- Digital rectal examination (DRE)
- Anoscopy or sigmoidoscopy, which is the insertion of a tube into the anus with a light to allow viewing of the interior of the anal canal.
- Biopsy of anal tissue – a small bit of the suspicious tissue is removed and examined by a pathologist.
- Female patients should have a gynecological exam with pap smear to check for cervical cancer, as both types of cancer are related to HPV (human papilloma virus).
- If lymph nodes are swollen, it may be possible to test for the presence of cancer cells.
- If cancer is found, further tests are done to determine if it has spread. These include a CT scan of the abdomen and pelvis, an ultrasound to examine the liver and an MRI to assess the pelvis.
For more information on tests used to diagnose cancer, see our Recommended Websites, Diagnostic Tests
Types and Stages
- Almost all anal cancers are squamous cell carcinomas, which start in the cells that line the anus.
- The rest are cloacogenic (basaloid transitional).
- Adenocarcinomas are the rarest and develop in anal ducts and glands.
- Very rarely, basal cell carcinomas and melanomas develop in the anus.
Staging describes the extent of a cancer. The TNM classification system is used as the standard around the world. In general a lower number in each category means a better prognosis. The stage of the cancer is used to plan the treatment.
T describes the site and size of the main tumour (primary)
N describes involvement of lymph nodes
M relates to whether the cancer has spread (presence or absence of distant metastases)
- Tis Carcinoma in situ.
- T1 Tumour is 2 cm or less
- T2 Tumour is between 2 cm - 5 cm
- T3 Tumour is more than 5 cm
- T4 Tumour of any size spreads to adjacent organ(s), e.g. vagina, urethra, bladder