A Randomized Controlled Trial to Investigate the Role of Low or High 'Fibre' Diets in Patients Undergoing Pelvic Radiotherapy - The Fibre Study
- To compare the efficacy of a high- vs low-fiber intervention in preventing bowel
toxicity in patients receiving radical pelvic radiotherapy treatment for gynecological,
urological (bladder), colorectal, or anal malignancy.
- To compare whether a high- or low-fiber intervention has any beneficial effect over no
intervention (i.e., ad-libitum fiber consumption).
- To examine the effect of a low- or high-fiber diet on gastrointestinal symptoms,
measured using the IBDQ-B and Bristol Stool Chart, in patients receiving radical
radiotherapy for pelvic malignancies.
- To minimize any potential risk associated with change in fiber intake by using a
controlled and gradual dietary-based intervention combined with dietetic advice.
- To examine the relationship between volume of irradiated bowel and onset of
gastrointestinal symptoms as measured by the Bristol Stool Chart.
- To measure percentage compliance with fiber prescription through validated dietetic
techniques including the 7-day Food Diary using household measures and the 24-hour
OUTLINE: Patients are stratified according to disease (gynecological vs gastrointestinal)
and concomitant therapy (received vs not received). Patients are randomized to 1 of 3
- Arm I (low-fiber diet): Patients are assessed by a qualified dietitian, receive written
guidance, and are counseled as to how best to meet their study fiber prescription of a
low-fiber diet, comprising 'not more than' 10 g of fiber per day for up to 7 weeks.
- Arm II (high-fiber diet): Patients are assessed by a qualified dietitian, receive
written guidance, and are counseled as to how best to meet their study fiber
prescription of a high-fiber diet, comprising a target of between 18 and 22 g of fiber
per day for up to 7 weeks.
- Arm III (no intervention): Patients receive advice designed to ensure they maintain
their normal habitual diet for up to 7 weeks.
All patients undergo radiotherapy once daily comprising approximately 25 (or more) fractions
in total to be delivered for 5-7 weeks in the absence of unacceptable toxicity.
All patients are asked to complete two 7-day Food Diaries at baseline and end of
radiotherapy treatment. All patients keep a daily record of stool characteristics and
frequency using the Bristol Stool Chart. Patients also complete a short 1-page weekly-cost
questionnaire to assess the economic impact of symptom management. Patients in arms I and II
complete several additional questions regarding the costs (if any) of adhering to their
fiber prescription and the palatability of the diet.
Blood and stool samples may be collected at baseline and during study therapy for biomarker
After completion of study treatment, patients are followed up for up to 1 year.
Allocation: Randomized, Masking: Open Label, Primary Purpose: Supportive Care
Change in IBDQ-B (Inflammatory Bowel Disease Questionnaire - Bowel Subset) score between baseline (i.e., Day 1 of radiotherapy treatment) and the nadir score during treatment
Peter R. Blake, MD
Royal Marsden NHS Foundation Trust