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 to let stool pass out of the body. Being infected with the human papillomavirus (HPV) can affect the risk of developing anal cancer.
Possible signs of anal cancer include bleeding from the anus or rectum or a lump near the anus. These and other symptoms may be caused by anal cancer. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:
- Bleeding from the anus or rectum
- Pain or pressure in the area around the anus
- Itching or discharge from the anus
- A lump near the anus
- A change in bowel habits