OBJECTIVES:
Primary
* 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.
Secondary
* 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 recall.
OUTLINE: Patients are stratified according to disease (gynecological vs gastrointestinal) and concomitant therapy (received vs not received). Patients are randomized to 1 of 3 treatment arms.
* 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 analysis.
After completion of study treatment, patients are followed up for up to 1 year.
