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Types of anal cancer

The type of anal cancer you have depends on the type of cell the cancer started in.

Squamous cell cancer

This is the most common type.  About 8 out of 10 anal cancers (80%) are squamous cell cancers. They are also called epidermoid cancers.

This type of anal cancer starts in squamous cells which make up the lining of the anal canal.

There are 3 types of squamous cell cancer:

  • large cell keratinising which start in the lower part of the anus - the cancer cells contain keratin (the protein in your hair and nails)
  • large cell non keratinising which start in the transitional zone of the anal canal - this is where the anal canal meets the rectum
  • basaloid

Many anal cancers have a mix of these cell types. Doctors treat all these squamous cell types of anal cancer in the same way.

Non epidermoid cancer

2 out of 10 anal cancers (20%) are a type called non epidermoid cancers. These are different from squamous cell anal cancers, so the treatment is different. 

There are different types of non epidermoid cancers, which are listed below. 

Adenocarcinoma 

This develops from the glandular cells that produce mucus in the anal canal. it is rare, and doctors treat it in the same way as rectal cancer.

Basal cell carcinoma

This is a type of skin cancer. It starts in the skin area around the anus.

Melanoma 

This is another type of skin cancer. It starts in skin cells called melanocytes. Doctors treat this type of anal cancer in the same way as melanomas.

Small cell cancers

Undifferentiated cancers

Last reviewed: 
30 Sep 2016
  • Anal cancer: ESMO-ESSO-ESTRO Clinical Practice Guidelines for diagnosis, treatment and follow-up
    R. Glynne-Jones and others.
    Annals of Oncology 2014. 25 (Supplement 3)

  • The differential diagnosis and interdisciplinary treatment of anal carcinoma
    D Raptis and others
    Dtsch Arztebl Int. 2015 Apr 3;112(14):243-9.

  • Principles and practice of oncology (8th edition)
    VT De Vita, S Hellman and SA Rosenberg
    Lippincott, Williams and Wilkins, 2008

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