Anal Cancer

The anus is an organ that lies at the end of the digestive tract below the rectum. It consists of two sections: the anal canal and the anus (or anal verge). The anal canal is a 3-4 cm long structure that lies between the anal sphincter (one of the muscles controlling bowel movements) just below the rectum and the anal verge which represents the transition point between the digestive tract and the skin on the outside of the body. Muscles within the anal canal and anus control the passage of stool from the rectum to outside the body.

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. The anal canal, the part of the anus between the rectum and the anal opening, is about 1½ inches long.

The skin around the outside of the anus is called the perianal area. Tumors in this area are skin tumors, not anal cancer.

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.

Tests that examine the rectum and anus are used to detect (find) and diagnose anal cancer

The treatment of cancer of the anus is different than the treatment of cancers around the anus. True anal cancers arise from the lining cells of the anus, the last portion of the gastrointestinal tract after the rectum. Cancers that arise outside of the anus in the skin are termed perianal skin cancers or anal margin cancers. These are treated as skin cancers and not as true anal cancers.
Although anal cancer is rare (comprising only 1.8% of all malignancies of the digestive tract), its incidence is on the rise. While the exact cause of anal cancer hasn't been determined, researchers have shown that it is highly associated with human papillomavirus (HPV) infection. HPV is the virus that is known to cause cervical cancer in women.

As with any cancer, treatment is dependent upon the type, size, and extent of spread (stage) of the particular tumor as well as the overall health status of the patient. Surgery is no longer the standard treatment for most forms of anal cancer, although this option was used routinely in the past. Formerly, anal cancers were treated with a surgical procedure known as abdominoperineal resection (APR). The procedure required removal of the anorectum and the creation of a permanent colostomy, an opening made in the abdomen through which feces pass out of the body to be collected in a special bag attached to the body.

Risk factors include the following:
Being over 50 years old.
Being infected with human papillomavirus (HPV).
Having many sexual partners.
Having receptive anal intercourse (anal sex).
Frequent anal redness, swelling, and soreness.
Having anal fistulas (abnormal openings).
Smoking cigarettes.