A trial looking at aspirin and fish oil as a possible way of preventing small growths forming in the bowel (seAFOod)

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

Cancer type:

Bowel (colorectal) cancer




Phase 3

This trial is looking to see if a type of fish oil, on its own or in combination with aspirin, can stop small growths on the bowel lining growing back after being removed. Doctors are keen to remove these small growths (polyps Open a glossary item) because there is a risk that they may develop into bowel cancer.

More about this trial

At the moment, the standard way of finding polyps is by having a camera test of the large bowel, called a colonoscopy. If polyps are there, they can be removed at the same time. Removing bowel polyps reduces the future risk of bowel cancer, but it does not prevent all cases of bowel cancer.

Doctors want to find a better way to reduce bowel polyps and reduce cancer risk.  One way is to treat people with drugs or food supplements after they have had polyps removed. This is called chemoprevention. Doctors also hope that it will reduce the number of colonoscopies each person needs, or possibly mean some people can stop having them altogether.

This trial is looking at a type of fish oil called eicosapentaenoic acid (EPA) and aspirin as a possible way of stopping polyps growing. We already know that fish oil can reduce the number and size of bowel polyps in people with a rare condition passed down in families. Doctors also think that taking daily aspirin helps prevent bowel polyps and bowel cancer, but they are not yet sure about the best dose, or who it would help most.

In this trial researchers want to test whether fewer polyps grow back when people who have had bowel polyps removed take fish oil alone or with aspirin.

Who can enter

You may be able to enter this trial if you

  • Are taking part in the Bowel Cancer Screening Programme - this could be either using the stool testing kit sent to you or having a camera test to look inside your lower bowel (bowel scope screening) as part of this programme
  • Have been told that you are ‘high risk’ for further polyps and bowel cancer after your screening camera test (colonoscopy), and need a repeat procedure in one year’s time
  • Are between 55 and  73 years old

You cannot enter this trial if you

  • Had a polyp that had become cancerous and you need to have treatment from the bowel cancer multi disciplinary team Open a glossary item
  • Take aspirin or another type of non steroidal anti inflammatory drug more than 3 times per week
  • Are sensitive to aspirin in any way
  • Have had an ulcer in your stomach or the first part of your small bowel (duodenum Open a glossary item) and you are not taking a drug to reduce acid, such as omeprazole
  • Are allergic to fish or seafood
  • Have a condition that runs in families and increases your risk of bowel cancer (familial adenomatous polyposis (FAP) or hereditary non-polyposis colorectal cancer (HNPCC)), or you carry the gene that causes either of these
  • Have had a type of inflammatory bowel disease, for example ulcerative colitis
  • Have had, or are due to have, part of your bowel removed
  • Have a condition that makes you likely to bleed easily
  • Are taking medication that stops your blood clotting easily, for example warfarin or clopidogrel
  • Have severe liver or kidney problems
  • Are taking the drug methotrexate at a dose of 15mg per week or higher
  • Are taking part in another clinical trial
  • Have any other condition that would make you unwell, or affect the results of the trial – you can check this with your doctor

Trial design

This trial is randomised. The people taking part are put into one of 4 groups randomly. Neither you nor your doctor will be able to decide or know which group you are in. People in

  • Group 1 will take fish oil capsules and aspirin
  • Group 2 will take dummy (placebo) capsules and aspirin
  • Group 3 will take fish oil capsules and a dummy tablet
  • Group 4 will take dummy capsules and a dummy tablet

Whichever group you are in, you take 3 capsules every morning, 2 capsules in the afternoon or evening, and one tablet once a day. You take these with food.

Before you start the trial medication you fill out a short questionnaire so that the team can work out how much fish oil is in your normal diet. This questionnaire should take about 10 minutes to complete. You repeat it when you complete the course of trial medication.

You take part in this trial for 12 months. The person who carries out tests on your bowels (Bowel Screening Practitioner) or research nurse will contact you every few months during the trial to see how you are getting on.

You finish the trial when you have seen the Screening Practitioner after your follow up colonoscopy, which is 12 months after your first one. This second colonoscopy is a routine part of the bowel screening programme. The team may collect tissue samples (biopsies) during this second colonoscopy. You then continue in the bowel screening programme as normal.

The team will ask to study polyp tissue from your first colonoscopy and any polyps found from your second colonoscopy.

If you need to have any more colonoscopies as part of the programme, the team would like to look at the results, for up to 6 years after you left the trial.  You do not have to agree to this if you don’t want to. You can still take part in the rest of the trial.

Hospital visits

The trial is designed to fit in with your bowel cancer screening care. The only extra visit you will need to make is 6 months after you joined the trial. You will see the team at this visit and collect your second 6 months worth of trial medication. The team will pay any travel expenses for this visit, up to the cost of £10.

You will give a blood and urine sample for the study

  • At your routine follow up appointment after your first colonoscopy
  • At the 6 months study visit
  • At your second routine colonoscopy appointment at 12 months

Side effects

Taking biopsies during your colonoscopy is a routine procedure and very safe.  There is a possible risk of tearing the bowel wall (perforation) or serious bleeding, but this is a very small risk as the biopsies taken are very small.

Possible side effects from fish oil include

  • Diarrhoea or loose stools
  • Feeling or being sick
  • Fishy after taste or bad breath

Possible side effects of using aspirin in this trial may include

  • A small amount of bleeding and bruising, for example when you have a blood test
  • Serious bleeding from the stomach or upper bowel (this is rare)
  • Risk of having a stroke (this is very rare)

Fish oil can slow blood clotting in a similar way to aspirin. Taking fish oil and aspirin together has not been tested in a clinical trial before. The team do not think there would be a problem, but to be on the safe side, they will ask you to stop the trial medication 10 days before your surgery, and not restart it until 4 days afterwards to prevent any possible risk of bleeding. They will also give you an information card to show your doctor or surgeon.

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

Professor Mark Hull

Supported by

Clinical Trials Unit of the University of Nottingham
Experimental Cancer Medicine Centre (ECMC)
NIHR Clinical Research Network: Cancer
NIHR Efficacy and Mechanism Evaluation (EME) Programme
University of Leeds

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.

Alan took part in a clinical trial for bowel cancer patients

A picture of ALan

“I think it’s essential that people keep signing up to these type of trials to push research forward.”

Last reviewed:

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