General Information About Anal Cancer
Key Points for This Section
Anal cancer is a disease in which malignant (cancer) cells form in the tissues of the anus.
The anus is the end of the large intestine, below the rectum, through which stool (solid waste) leaves the body. The anus is formed partly from the outer skin layers of the body and partly from the intestine. Two ring-like muscles, called sphincter muscles, open and close the anal opening and let stool pass out of the body. The anal canal, the part of the anus between the rectum and the anal opening, is about 1-1½ inches long.
See the following PDQ summary for more information about anal cancer:
Squamous cell carcinoma is the most common type of anal cancer.
Another type of anal cancer, called anal adenocarcinoma, is very rare and is not discussed in this summary.
In the United States, the number of new cases of anal cancer has increased in recent years.
From 2001 to 2010, new cases of anal cancer and deaths from anal cancer increased each year. The increase in new cases was slightly higher in women and the increase in deaths from anal cancer was slightly higher in men.