Anal precancer is a growth and/or changes in the skin cells in the anal region. The existence of a 'precancerous' condition is not a cancer diagnosis, which is very important to remember. These conditions are very important precursors to cancer, however, and must be monitored, and treated if appropriate, to reduce the risk of them developing into cancer.

Regular screening, monitoring and rapid treatment are the best ways to protect yourself if you think you may be at risk. We hope that the information you find here will help you identify and manage any potentially precancerous conditions.

What is anal precancer?

There are many types of growths that can develop in the anus, but not all of them are cancerous. Some start off as non-cancerous (or 'benign) but later develop into cancer. It is these growths that are called 'precancerous'.

All growths and abnormal changes in the epithelial (skin) cells in and around the anal area are known as AIN (anal intraepithelial neoplasia). These changes are associated with infection with HPV (the human papillomavirus), which is a risk factor for anal cancer.

You may be familiar with these kinds of changes due to knowledge of, or experience with, cervical precancer. Cervical precancer is also caused by HPV and causes similar lesions on the cells of the cervix and anus. Unlike cervical precancer, both men and women are at risk of anal precancer because both men and women have anuses.

Changes and growths can develop on the outside of the anus as well as on the inside – and sometimes in both places at once. Symptoms include bleeding and itching in this area, although sometimes there are no symptoms at all. In the majority of cases, AIN will disappear by itself and will not develop any further. You may not even be aware that you've had it. Many people who have HPV do not experience symptoms and do not know that they’ve had it.

If you have unusual itching or bleeding in this region, please go to your medical provider to discuss your symptoms as soon as possible. If you are found to have anal precancer, it is important to take the appropriate steps as outlined by your healthcare provider to prevent the development of cancer. Even with treatment and monitoring it is possible for precancerous AIN to develop into anal cancer.

There are three different levels of AIN:

AIN1:
  • This is not considered precancerous.
  • AIN 1 is also known as 'mild dysplasia', or LSIL, which means 'low-grade squamous intraepithelial lesion'. Dysplasia is the general term for all abnormal changes in cells. The dysplasia is classified by the severity of the changes, i.e. mild, moderate or severe.
  • These cells often look very similar to normal, healthy cells.
  • Anal warts, also called condyloma, are a type of AIN1. As they are easily identifiable, warts are usually how people find out about their anal HPV infection. Warts are usually caused by HPV types 6 and 11.
AIN2 and AIN3:
  • These are more severe changes in the appearance of epithelial cells.
  • They are precancerous.
  • AIN2 and AIN3 are also known as 'moderate to severe dysplasia', or HSIL which means 'high-grade squamous intraepithelial lesion'.
  • Most cases of AIN2 and AIN3 stay the way they are (sometimes for decades) or go away on their own. However, if an individual does not regularly visit a doctor regarding their AIN to be monitored and/or treated, there is the risk that they might develop into cancer.
  • There is no completely accurate way of determining whether someone’s AIN2 or AIN3 will turn into cancer, or how long this will take. Careful and frequent screening and monitoring is therefore recommended.
  • AIN2 and AIN3 are most commonly caused by HPV types 16 and 18.

AIN2 and AIN3 tend to be more common in HIV-positive individuals, although HIV-negative individuals develop them as well.

The types of changes that lead to anal precancer are also found in the cervix, vagina, vulva and penis. HPV infection is thought to cause most of these cancers, too. Cancers of these areas which are caused by HPV also have precancerous stages. Other risk factors that may increase your chances of getting anal precancer are smoking, being a transplant recipient and being an older individual (50-80 years old). If you have, or have had HPV, or any of these other conditions, you may be at a higher risk of developing AIN, and should consider getting screened for it even if you are not experiencing symptoms. There is currently ongoing research in the medical community about who should be routinely screened for anal precancer and cancer.

How do I get screened?

Doctor diagnosing patient

If you think you may have AIN or are at risk, it is suggested that you have a clinician screen you.

Screening involves visual inspection. However, appropriate and accurate screening should also include additional methods, as a visual check alone can fail to diagnose AIN that is inside the anal canal and any subtle changes. Additional screening options include:

  • Digital ano-rectal exams or 'DARE:' a doctor places his or her fingers inside the anal canal to feel for abnormalities. The purpose of this test is to look for abnormal masses or growths, so if you think you may have precancer, request this additional testing.
  • An anal pap test: similar to a routine cervical pap test and involves sampling cells inside the anus to detect changes and abnormalities.
  • Anoscopy: a tube called an anoscope is placed inside the anus and a strong light illuminates the tissue.
  • High-resolution anoscopy or HRA: a more advanced ansocope with a high-resolution magnifying glass is used to examine and evaluate the tissue in the anus. This is the most precise examination for anal cancer and precancer.

Screening Guidelines

Routine screening guidelines for anal cancer or precancer have yet to be universally adopted because there have not yet been enough studies for the government and medical communities to recommend routine screening. The predominant guidelines tend to focus only on HIV-positive individuals. New York State, for example, recommends annual anal pap smears for HIV-positive men and women.

There is increasing evidence to support screening for precancers. The NIH is currently funding what is known as the ANCHOR study, which will be the first randomised control trial for anal precancer screening efficacy and treatment. This is the first study that the NIH has ever supported on anal precancer screening. It is hoped that standards of care will be developed from this study and embraced by the government and medical community.

Where Can I Get Screened?

Please see our Medical Resources page to find a clinician providing screening services in your area.

Precancerous conditions can disappear on their own, without needing treatment. However, it is important to be frequently monitored if you are presenting with dysplasia. Also, please remember that even with the care and treatment practices in effect now, recurrence is still possible. This is especially so for those individuals considered high risk, such as people living with HIV. Regular screening, monitoring and rapid treatment are therefore essential for anyone who thinks they may be at risk.