A randomized double blind placebo controlled multicenter study of mesalazine for the prevention of acute radiation enteritis.

BACKGROUND AND PURPOSE: Symptoms of acute radiation enteritis (ARE), dominated by diarrhea, occur in more than 70% of patients receiving pelvic irradiation. Eicosanoids and free radicals release have been implicated in the pathogenesis. Mesalazine (5-ASA) is a potent inhibitor of their synthesis in the mucosa and could therefore be of some interest in preventing ARE.

PATIENTS AND

METHODS

The study was performed in six radiotherapy units in France who agreed on standardized irradiation procedures. One hundred and fifty-three patients planned for external beam radiotherapy to the pelvis > or = 45 Gy for prostate (n = 97) or uterus (n = 54) cancer were randomized on a double blind basis to receive prophylactic 5-ASA (4 g/day Pentasa) or placebo. Patients with concomitant chemotherapy were excluded. Prostate and uterus cancers were chosen since these centropelvic tumors require a similar radiotherapy protocol during the first step of treatment and involve a comparable volume of small intestine. The symptoms of ARE and their severity were assessed every week during irradiation, and 1 and 3 months after its end. All patients followed a low fiber and low lactose diet. End points were diarrhea, use of antidiarrheal agents, abdominal pain, and body weight. Effficacy was evaluated using intention to treat.

RESULTS

(means +/- SD) Groups did not differ for age (mean 64 +/- 9 years), sex, tumor site, or irradiation procedure. During irradiation, diarrhea occurred in 69% and 66% of the 5-ASA and placebo groups, respectively (chi2, P = 0.22). Curves of survival without diarrhea did not differ between groups (logrank P = 0.09). Severity of diarrhea did not differ between groups except at d15 where it was significantly more severe in the 5-ASA group (ANOVA P = 0.006). Duration of diarrhea did not differ (22 +/- 15 days in both groups, P = 0.88). Abdominal pain was less frequently reported in the 5-ASA group at d28 (34% vs. 51%, P = 0.048). Use of antidiarrheal agents and body weight did not differ between groups.

CONCLUSION

Mesalazine 4 g/day did not decrease the symptoms of ARE.