A study of how laser treatment affects the function of the anus (FLAN)

Please note - this trial is no longer recruiting patients. We hope to add results when they are available.

Cancer type:

Anal cancer





This study is looking at laser treatment for abnormal cells around the anus. It is looking at how the treatment affects the function of the anus.  

These abnormal cells are called anal intraepithelial neoplasia (AIN). This study is open to men who have sex with men and have high grade Open a glossary item AIN.

More about this trial

High grade AIN means that the cells around and in the anus look very abnormal and could develop into anal cancer. You are at higher risk of anal cancer if you are a man who has sex with men. 

One treatment for AIN is using lasers to remove the abnormal cells. The long term effects of laser treatment on the function and structure of the anus aren’t known. These effects could include changes:

  • to when you go to the toilet
  • in stopping poo (faeces) or gas from leaking out
  • to when you use it to have sex (if you do)

In this study the researchers want to find out more about these long term effects. The team are also looking at what sensations you have in the anus when you have the laser treatment.

To find this out you have 3 tests before your treatment and the same tests sometime after. These test the function and structure of the anus. 

The aims of this study are to find:

  • whether there are any changes to the function of the anus after having laser treatment
  • out if treatment affects quality of life Open a glossary item

Who can enter

The following bullet points are a summary of the entry conditions for this study. Talk to your doctor or the study team if you are unsure about any of these. They will be able to advise you. 

Who can take part

You may be able to join this study if all of the following apply. You:

  • are a man who has sex with men
  • have high grade squamous cell anal intraepithelial neoplasia 
  • are either HIV positive or negative. If you are HIV positive you must have a CD4 count above 350, if less then you must have been on highly active antiretroviral treatment for at least 3 months
  • must have disease in the anal canal
  • are over 18 years old

Who can’t take part

You cannot join this study if any of these apply. You:

  • have or had anal cancer
  • had previous laser treatment or another type of treatment that destroys the abnormal tissue around the anus (ablative treatment) 
  • had any treatment for your high grade squamous cell anal neoplasia in the past 2 months
  • have or had any severe medical condition such as inflammatory bowel disease or an abnormal hole (fistula) that needed surgery
  • have severe haemorrhoids (piles) that need surgery
  • have an abnormal hole (fistula) in the anus
  • have an infection around the anal area

Trial design

This is a pilot study. The team need 20 men to join. 

You have the laser treatment at the Homerton University Hospital. 

You see the study team to have 3 tests and to fill in some questionnaires before your laser treatment. These are usually done on the same day as your treatment.

Strength test
This tests the function or strength of the muscles in your anus. The researcher puts a thin plastic coated tube (4mm) just into the anus. It measures the pressure of the muscles when at rest and when you squeeze your anus shut. They inflate a balloon in your back passage (rectum) to see how sensitive it is. This test takes about 10 minutes. 

Structure of the anus test
In this test they put a 2cm ultrasound probe with lubricant jelly on it into your anal canal. It takes an ultrasound scan of the anal muscles. This takes 5 to 10 minutes. 

Sensation test
For this test they put a ring like a small butt plug into the anus. A low level electric current goes through the ring. At first you won’t feel it. As they increase the stimulus (electric current) you will feel a tingling sensation. When you say you feel this tingling they stop the test. They repeat this test again. This test takes about 5 minutes. 

All these tests have a long track record and are safe to use. People don’t usually mind having them.

The team tell you the results of the tests and what they mean. 

You have the same 3 tests repeated 6 months after treatment. 

You fill in a few questionnaires:

  • before treatment
  • 4 weeks later and then
  • 6 months after treatment

The questions ask about:

  • any pain you might have
  • any problems controlling your bowel movements
  • your sexual activity 
  • your quality of life

Hospital visits

You have the tests and the treatment at a specially designed ward at the Homerton University Hospital. 

The study team phone you 4 weeks after treatment to find out how you are and to ask you the questions in the questionnaires.

They then see again at 6 months to do the 3 tests. This is the usual time for your follow up after the laser treatment.

Side effects

These 3 tests are safe. The study team don’t expect any side effects from them. But if you feel any discomfort during the tests tell the researcher and they will stop the test.

Your doctor will tell you about the laser treatment.

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Tamzin Cuming

Supported by

Homerton University Hospital NHS
University College London (UCL)

If you have questions about the trial please contact our cancer information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Wendy took part in a new trial studying the possible side effect of hearing loss

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"I was delighted to take part in a clinical trial as it has the potential to really help others in the future.”

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