What are the types of anal cancer?
Anal cancer is often classified according to where in the anus it develops, whether in the anal canal or in the anal margin, which is the outer opening. Treatment often depends on where the cancer is located. Anal cancer that is confined to the inner surface layer of the anus is called carcinoma in situ (CIS) or Bowen disease. This type of cancer is often classified as precancerous.
Cancer that spreads beyond the anus is known as invasive anal cancer. These can be: