Clinical trial: Efficacy of a low or modified fat diet for the prevention of gastrointestinal toxicity in patients receiving radiotherapy treatment for pelvic malignancies

Abstract

Background: Inflammatory responses to pelvic radiotherapy can result in severe changes to normal gastrointestinal function with potentially severe long-term effects. Reduced or modified fat diets may confer benefit.

Methods: This randomised controlled trial recruited patients with gynaecological, urological or lower gastrointestinal malignancy due to receive radical radiotherapy. Patients were randomised to a low fat (20% total energy from long chain triglycerides), modified fat (20% from long chain triglycerides and 20% from medium chain triglycerides) or normal fat diet (40% total energy from long chain triglycerides). The primary outcome was a difference in change in Inflammatory Bowel Disease Questionnaire--Bowel (IBDQ-B) score, from the start to end of radiotherapy.

Results: A total of 117 patients with pelvic tumours (48% urological; 32% gastrointestinal; 20% gynaecological), with mean (SD) age: 65 (11.0) years, male:female ratio: 79:38, were randomised. The mean (SE) fall in paired IBDQ-B score was -7.3 (0.9) points, indicating a worsening toxicity. Differences between groups were not significant: P = 0.914 (low versus modified fat), P = 0.793 (low versus normal fat) and P = 0.890 (modified versus normal fat). The difference in fat intake between low and normal fat groups was 29.5 g [1109 kJ (265 kcal)] amounting to 11% (of total energy intake) compared to the planned 20% differential. Full compliance with fat prescription was only 9% in the normal fat group compared to 93% in the low fat group.

Conclusions: A low or modified fat diet during pelvic radiotherapy did not improve gastrointestinal symptom scores compared to a normal fat intake. An inadequate differential in fat intake between the groups may have confounded the results.