A trial to see if fibre can help to control side effects in people having radiotherapy that affects the bowel

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

Cancer type:

Anal cancer
Bladder cancer
Bowel (colorectal) cancer
Cervical cancer
Colon cancer
Ovarian cancer
Rectal cancer
Vaginal cancer
Vulval cancer
Womb (uterine or endometrial) cancer




Phase 1

This trial is looking at whether eating more or less fibre improves radiotherapy side effects to the bowel, in people having treatment to the area between their hip bones (pelvic radiotherapy).

If you have cancer, you may have radiotherapy as part of your treatment. Radiotherapy destroys cancer cells in the treated area. But it also affects healthy cells that are close by. New ways of giving treatment help to protect healthy tissue, but it can still be affected.

If you have radiotherapy to the organs in the area between your hip bones (your pelvis Open a glossary item), your digestive system can become inflamed Open a glossary item. This can cause loose stool, diarrhoea and difficulty controlling your bowels.

Researchers in this trial are interested in how we can use diet to protect healthy digestive system Open a glossary item tissue. In this trial, they want to see whether diets high or low in fibre Open a glossary item are better for people having radiotherapy. Asking people to reduce their fibre may help to stop the bowels opening too much. But increasing fibre may soak up more water from the bowel and give a better structure to the stool, making it pass through more slowly and steadily. Both approaches seem to make sense. But we need more research to find out which advice is best. The researchers believe that stopping these bowel symptoms happening may make treatment easier to give. And reduce the risk of long term side effects. The main aims of this trial are to see

  • If changing the amount of fibre you eat during your course of radiotherapy affects side effects
  • Whether the amount of bowel that gets a particular dose of radiotherapy affects the side effects you have

Who can enter

You can enter this trial if you

You cannot enter this trial if you

  • Are not able to eat
  • Are not able to digest wheat, or you need to avoid foods containing gluten (coeliac disease Open a glossary item)
  • Are on a diet aimed at decreasing frequency of your bowel movements (a low residue diet), for a medical reason
  • Have a tube fitted to relieve a blockage or keep open an area of your digestive system (gastrointestinal stent)
  • Have a feeding tube going into your stomach (PEG tube) or the part of your small intestine called the jejunum (PEJ or JEJ tube)
  • Have had surgery to form an opening of the bowel onto the surface of your tummy (colostomy)
  • Are taking part in another study looking at side effects of treatment

Trial design

This trial will recruit 177 people into 3 groups. This is a randomised trial. The people taking part will be put into groups by a computer. Neither you nor your doctor will be able to decide which group you are in. During your radiotherapy, you will either

  • Start a low fibre diet
  • Start a high fibre diet
  • Carry on with the same types of food you usually eat

Everyone will meet with a dietician Open a glossary item to discuss the amount of fibre the trial team would like them to eat, based on the group they are in. If you are in groups 1 or 2 you will also have a booklet to help you work out how much fibre is in the food you eat. If possible, the team would like you to try out your new diet before you start radiotherapy. This is so they can help you sort out any problems before you start the diet on your first day of radiotherapy.

You will keep a food diary during the first and last weeks of your radiotherapy. And complete a chart to record and describe your stools throughout your treatment. You will meet the trial team to fill out a questionnaire each week and at the end of treatment. This will ask about your side effects, your diet and how you are managing. For these meetings, you will need to remember the food you ate the day before.

The trial team would also like to find out more about any extra costs you may have had in dealing with any radiotherapy side effects. If you are in groups 1 or 2, they will also ask about any costs involved in changing your diet and whether you enjoyed the diet.

Everyone will give a blood and stool sample

  • When they start radiotherapy
  • Halfway through their course of radiotherapy
  • A year after treatment

You give your blood sample at the same time as any routine blood test you may be having. Both types of sample will help the team understand more about the changes that happen in your body during radiotherapy.

The team may ask if you would be willing to have 3 extra CT scans. This will help them to see how much of your radiotherapy is getting to your healthy bowel as well as to the treatment area. They will then see if there is a link between this and any bowel symptoms you have. These scans will be similar to CT scans you may have had before. The only difference is that you will drink a pint of fruit flavoured drink (contrast) before your scan. This shows the team an outline of your bowel on the scan, and helps them to measure what they see more easily.

Throughout the trial, you stay under the care of your regular cancer doctors.

Hospital visits

You will make an extra hospital visit to see the dietician before you start your radiotherapy, to discuss your trial diet. You will also see the trial team a year after treatment.

If you agree to have the extra CT scans you will have these when you are already at the hospital for your radiotherapy. These scans last about an hour.

Everything else you do to take part in the trial will be during your hospital visits for your radiotherapy.

Side effects

If you are in groups 1 or 2, you may have a change in your bowel habit as a result of changing how much fibre you eat. Because this fibre change is linked to the food you eat rather than fibre medication, your body should gradually get used to the change.

If you have the extra CT scans, the amount of extra radiation you will have is very small compared to your radiotherapy.

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

Dr HJN Andreyev
Dr S Essapen

Supported by

The Royal Marsden NHS Foundation Trust

Questions about cancer? Contact our information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:

Oracle 6814

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

Cara took part in a clinical trial

A picture of Cara

"I am glad that taking part in a trial might help others on their own cancer journey.”

Last reviewed:

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