A randomized trial to assess the efficacy of 5-aminosalicylic acid for the prevention of radiation enteritis.

Sulphasalazine is an effective treatment for diarrhoea occurring during pelvic radiotherapy. We report the results of a trial to assess the value of its active moiety, 5-aminosalicylic acid, (5-ASA) in a prophylactic setting. Seventy-three patients planned for external beam radiotherapy to the pelvis were randomized on a double-blind basis to receive prophylactic 5-ASA or placebo. The severity of the acute radiation bowel reaction was documented by a weekly questionnaire. Surprisingly, diarrhoea occurred in a higher proportion of patients in the 5-ASA arm than the placebo arm (91.2% versus 73.7%, P = 0.070). The maximum change in both the severity of diarrhoea and the number of days per week on which diarrhoea occurred (from pre-radiotherapy level to the worst level at any time during treatment) were both significantly greater in patients taking 5-ASA than those taking placebo (P = 0.014 and P = 0.026, respectively). The average change (the sum of the weekly scores divided by the number of weeks of treatment, minus the pre-radiotherapy score) for both severity and days per week of diarrhoea were again greater in the 5-ASA than the placebo arm, but failed to reach statistical significance (P = 0.095 and P = 0.079, respectively). The use of anti-diarrhoeal medicines was significantly greater in the 5-ASA arm (P = 0.011). Constipation was more common in the placebo arm but this did not reach significance (P = 0.20). 5-ASA thus has no protective effect against acute radiation enteritis and appears to worsen it. Possible reasons for this surprising finding are discussed.

RCT Entities:   Population Interventions Outcomes