[Interventional trial for colorectal cancer prevention in Osaka]

We established a protocol for an interventional randomized controlled trial for the prevention of colorectal tumors, in which special importance was attached to practicality. The subjects are patients with multiple colorectal tumors, who form a high risk group for colorectal cancer. Two regimens were formulated for the prevention of colorectal cancer. One was dietary guidance alone (Regimen I), and the other was dietary guidance plus the ingestion of wheat bran biscuits (Regimen II). One of the two regimens is assigned at random each week in advance, and the patients are recruited to receive the regimen of the week in which they are first examined, after giving informed consent. The dietary guidance aims to restrict the energy intake of oil and fat to 18-22% of the total energy intake. Biscuits with a wheat bran content of 30% by weight, which we developed, were prescribed at 25 g/day (7.5 g/day as wheat bran). The main end points of the trial were examinations for recurrence of colorectal tumors after 4 years. The target number of patients is 200 in total, i.e., 100 for each group. The recruiting of subjects was started in June, 1993, and finished in September, 1997; 100 (90%) of 115 patients recruited for Regimen I and 100 (88%) of 116 patients recruited for Regimen II consented to participate in the trial. No severe adverse effects have been reported, and the trial is progressing well. The trial will be completed in September, 2001, when the 4-year follow-up of the last patient will end.