Anal cancer is a cancer which arises from the anus, the distal opening of the gastrointestinal tract. Symptoms may include bleeding from the anus or a lump near the anus. Other symptoms may include pain, itchiness, or discharge from the anus. A change in bowel movements may also occur.

Risk factors include human papillomavirus (HPV), HIV/AIDS, receptive anal sex, smoking, and many sexual partners. Anal cancer is typically a squamous cell carcinoma. Other types include adenocarcinoma, small cell carcinoma, and melanoma. Diagnosis is suspected based on physical examination and confirmed by tissue biopsy.

Prevention includes avoiding risk factors and HPV vaccination. Standard treatment may include radiation therapy, chemotherapy, and surgery. About 8,300 people are diagnosed a year in the United States, representing about 0.5% of new cancers. Onset is typically after the age of 45. Women are affected more often than men. The number of cases has increased since the 1990s. The five-year survival rate in the United States is 68%.

Symptoms of anal cancer can include pain or pressure in the anus or rectum, a change in bowel habits, a lump near the anus, rectal bleeding, itching or discharge. Bleeding may be severe.

Most anal cancers are squamous cell carcinomas (epidermoid carcinomas), that arise near the squamocolumnar junction. It may be keratinizing (basaloid) or non-keratinizing (cloacogenic).

Other types of anal cancer are adenocarcinoma, lymphoma, sarcoma or melanoma.

Pathologic TNM staging of anal carcinomas:

Primary tumor (pT)