Anal Cancer

UW Health Colon and Rectal Surgery specialists in Madison, Wisconsin provide comprehensive evaluation and surgical treatment of diseases of the colon, rectum and anus.


The anal canal is a passage that connects the rectum to the outside of the body. Anal cancer occurs in the cells surrounding the anal opening or in the canal.


Anal cancers develop from skin cells and are called squamous cell carcinomas. Cells that are becoming malignant but have not invaded deep to the skin are referred to as "high grade dysplasia", "carcinoma-in-situ" or "Bowen's disease".


Overview of Anal Cancer


Anal cancer is fairly uncommon. It accounts for about 1-2 percent of gastrointestinal cancers. Approximately 8,000 new cases of anal cancer are diagnosed each year in the U.S.A., with about half being in women. About 1,000 people will die of the disease each year. This may be compared to 140,000 new cases of colorectal cancer with 50,000 deaths per year.


Risk Factors for Anal Cancer


Anal cancer is commonly associated with the human papilloma virus (HPV). This virus causes warts in and around the anus and on the cervix in women. It is associated with an increased risk of cervical cancer in women.


Additional risk factors include:

  • Age
  • Anal sex
  • Smoking
  • Suppressed immune system
  • Chronic local inflammation
  • Pelvic radiation

Preventing Anal Cancer


While it is not possible to totally prevent cancer, there are ways to reduce your risk of developing the disease, including:

  • Ask your provider about the HPV vaccine and if you should get it
  • Get regular checkups
  • Practice safe sex
  • Not smoking or quitting smoking. For help with smoking cessation, call the Wisconsin Tobacco Quit Line (1-877-270-STOP)

For high-risk individuals, anal cancer screening may be performed and includes an anal pap smear, anoscopy, and/or high resolution anoscopy.


High-risk individuals include:

  • People living with HIV
  • Individuals with multiple sexual partners
  • Women with a history of cervical warts or precancerous changes of the cervix
  • Anal cancer symptoms

Symptoms of anal cancer can include:

  • Bleeding from the rectum or anus
  • A lump or mass at the anal opening
  • Pain in the anal area
  • Persistent or recurrent itching
  • Change in bowel habits (having more or fewer bowel movements) or increased straining during a bowel movement
  • Narrowing of the stools
  • Discharge (mucous or pus) from the anus
  • Swollen lymph nodes (glands) in the anal or groin areas

These symptoms can also be caused by less serious conditions such as hemorrhoids, but you should never assume this. If you have any of these symptoms, see your doctor.


Diagnosing Anal Cancer


An abnormal anal pap smear or the presence of symptoms should lead to examination of the anal canal. If an abnormal area is identified, based on your doctor's exam, a biopsy will be performed to determine the diagnosis. If the diagnosis of cancer is confirmed, additional tests to determine the extent of the cancer may be recommended.


Treating Anal Cancer


Treatment for most cases of anal cancer is very effective. There are three basic treatments used for anal cancer:

Common Questions About Anal Cancer


Will I need a colostomy?


The majority of patients treated for anal cancer will not need a colostomy. If the tumor does not respond completely to combination therapy, if it recurs after treatment, or if it is an unusual type, removal of the rectum and anus and creation of a colostomy may be necessary. This operation is known as an an abdomino-perineal resection (APR).


What happens after treatment for anal cancer?


Follow-up care to assess the results of treatment and to check for recurrence is very important. Most anal cancers are treated effectively. In addition, many tumors that recur may be successfully treated if they are caught early. A careful examination by an experienced physician at regular intervals is the most important method of follow-up. Additional studies may be recommended. You should report any symptoms or problems to your doctor right away.