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Anal Cancer

Anal Cancer | ASCRS

Alternate Titles: 
Talking With Your Healthcare Provider About Colorectal Cancer
Six Steps to Lowering Your Risk of Colon Cancer
Self-Test on Colorectal Cancer


The anal canal is a short tube surrounded by muscle at the end of your rectum. The rectum is the bottom section of your colon (large intestine). When you have a bowel movement, stool leaves your body from the rectum through the anal canal. Cancer begins when some of the body’s cells divide without stopping. As the cancer grows, it may stay in nearby tissues or spread to other parts of the body, a process called metastasis. Anal cancer starts in the cells around or just inside the anal opening. A person may be diagnosed with precancerous cells in the anal area. With time, these cells may have a high chance of becoming cancerous. While this condition is treated differently than anal cancer, it is the reason to get treatment early.


  • In 2016, about 8,000 adults in the U.S. will be diagnosed with anal cancer, and it is believed that 1,080 people will die from the disease.
  • About two-thirds of anal cancers affect women.
  • Anal cancer accounts for about 1-2% of all cancers of the intestines.
  • Anal cancer most often affects people ages 55-64.
  • Far less common than colorectal cancer, anal cancer affects about one in 500 people in their lifetime versus one in 22 people. The number of anal cancer cases has been steadily growing for years.
  • Only a small number of anal cancers spread, but when they do, the disease is difficult to treat. Anal cancer spreads most often to the liver and the lungs.


A risk factor increases your chance of getting a disease. The most common risk factor for anal cancer is being infected with the human papilloma virus (HPV). HPV is a sexually transmitted virus that may also cause warts in and around the anus or genitals in both men and women, but anal cancer can occur without the presence of warts. Other risk factors include:

  • Age (55 and older)
  • Anal sex
  • Sexually transmitted diseases
  • Multiple sex partners
  • Smoking
  • History of HPV-related cancers, especially cervical
  • Weakened immune system due to HIV, chemotherapy, or having an organ transplant
  • Chronic inflamed areas that cause long-term redness or irritation, such as anal fistulas or open wounds in the anal area
  • Prior pelvic radiation therapy for rectal, prostate, bladder, or cervical cancer.


Although few cancers are totally preventable, avoiding risk factors and getting regular checkups are important. Using condoms may reduce, but not get rid of the risk of HPV infection. HPV vaccines (for those ages 9 to 26) have been shown to not only lower the risk of HPV infection, but also reduce the risk of anal cancer in men and women. People at increased risk should talk to their physicians about getting an anal cancer screening. During this test, your physician swabs the anal lining, looking at the cells under a microscope for anything unusual. Other forms of screening include looking closely at the area during a surgery, or in the office with a special scope to look in the anal canal. Early identification and treatment of precancerous areas may help prevent anal cancer. 


As many as 20% of patients with anal cancer may not have symptoms. The following symptoms can be seen with anal cancer, but may also be caused by less serious conditions such as hemorrhoids. However, if you notice any of these, see your physician as soon as possible.

  • Bleeding from the anus or rectum
  • Pain in the anal area
  • A mass or growth in the anal opening
  • Lasting anal itching
  • Change in bowel habits, e.g. having more or fewer bowel movements or more straining during a bowel movement
  • Narrowing of the stools
  • Discharge, mucous, or pus from the anus
  • Swollen lymph glands in the anal or groin area


Many anal cancers are found early because they are in a location that your physician can easily see and reach. Diagnosis is often made when people with any of the above symptoms undergo an anal exam. Anal cancer may also be found incidentally during yearly physical exams that include a digital rectal exam. The rectal exam is performed to check the rectum, prostate or other pelvic organs. Anal cancers can also be found when a person has a preventive colorectal screening test (such as a colonoscopy).


  • A digital rectal exam in which your physician inserts a gloved, lubricated finger into the anus and rectum to feel for lumps or other abnormalities.
  • Exam of the anal canal with a small, lighted scope (anoscopy) to visualize any abnormal areas.
  • Biopsy, in which sample tissue is snipped from the area in question and tested to make an accurate diagnosis.
  • Anal ultrasound, MRI, or other imaging tests to determine the extent of cancer after a confirmed diagnosis is made. 


Most cases of anal cancer have high cure rates when treated early. There are three basic types of treatment:

  • Surgery – an operation to remove the cancer
  • Radiation therapy – high-dose X-rays that kill cancer cells
  • Chemotherapy – drugs that kill cancer cells

Combination therapy with radiation and chemotherapy is considered the gold standard treatment for most anal cancers. Sometimes, very small or early-stage tumors may be removed surgically without the need for further treatment. If the cancer is advanced, major surgery may be required to remove the tumors. 


This is a commonly asked question. A colostomy is when the end of the colon (large intestine) is brought through an opening (stoma) in the abdominal wall. A bag is attached to the outside of the patient’s belly to collect bowel movements.

In the majority of cases, a colostomy is not required, as many cancers can be cured with chemotherapy and radiation alone. A colostomy may be needed if the tumor does not respond well to therapy or recurs after treatment. For advanced anal cancers or unusual types, the surgeon may need to remove the rectum and anus and create a permanent colostomy. Sometimes this is the only way to remove all the cancer cells.


Most anal cancers are cured with combination therapy. If caught early, many cancers that come back after nonsurgical treatment are treated effectively with surgery. While combination radiation/chemotherapy produces more side effects, this approach also results in the best long-term survival rates. After completing this treatment, as many as 70-90% of patients are still alive and cancer free at 5 years.

Regular follow-up with a careful exam by your colon and rectal surgeon is important. During the appointment, he or she will assess the results of treatment and check to see if there are any new signs of anal cancer. In some instances, additional studies may be needed.


Colon and rectal surgeons are experts in the surgical and non-surgical treatment of diseases of the colon, rectum and anus. They have completed advanced surgical training in the treatment of these diseases as well as full general surgical training. Board-certified colon and rectal surgeons complete residencies in general surgery and colon and rectal surgery, and pass intensive examinations conducted by the American Board of Surgery and the American Board of Colon and Rectal Surgery. They are well-versed in the treatment of both benign and malignant diseases of the colon, rectum and anus and are able to perform routine screening examinations and surgically treat conditions if indicated to do so.


The American Society of Colon and Rectal Surgeons is dedicated to ensuring high-quality patient care by advancing the science, prevention and management of disorders and diseases of the colon, rectum and anus. These brochures are inclusive but not prescriptive. 
Their purpose is to provide information on diseases and processes, rather than dictate a specific form of treatment. They are intended for the use of all practitioners, health care workers and patients who desire information about the management of the conditions addressed. It should be recognized that these brochures should not be deemed inclusive of all proper methods of care or exclusive of methods of care reasonably directed to obtain the same results. The ultimate judgment regarding the propriety of any specific procedure must be made by the physician in light of all the circumstances presented by the individual patient. 


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