Is adenocarcinoma following esophagoduodenostomy without carcinogen in therat reflux-induced?

Background. A widely used rat model for reflux-induced esophageal adenocarc inoma in the absence of carcinogens involves induction of duodenoesophageal reflux by performance of esophagoduodenostomy. The aim of this study was t o test the hypothesis that acid reflux reduces the incidence of adenocarcin oma in this animal model. Methods. One hundred ninety 8-week-old male Sprague-Dawley rats were studie d. The animals were randomly divided into four groups with a different type of reflux established in each group. Group 1 had an esophagoduodenostomy f or duodenogastroesophageal reflux (n = 59), group 2 had an esophagoduodenos tomy and a total gastrectomy for duodenoesophageal reflux (n = 54), group 3 had an esophagoduodenostomy and a total gastrectomy with acid supplementat ion with acidified water to control for the effect of the gastrectomy (n = 50), and group 4 had a total gastrectomy with Roux-en-Y reconstruction to e liminate all reflux (n = 25), One hundred eighty-eight surviving animals we re sacrificed at 36 weeks of age and the resected esophagi were examined. Results. All animals except the no reflux control group had severe reflux e sophagitis. The frequency of tumor development was similar in all study gro ups. All of the tumors were well-differentiated adenocarcinomas that were l ocated on the external surface of the bowel either at or immediately distal to the esophagoenteric anastomosis. The tumors appeared to arise from the submucosa and did not involve the overlying mucosa, There was no definite e vidence of columnar lining of the esophagus but an admixture of squamous an d columnar epithelium was found microscopically in all groups, This finding was unrelated to the presence and composition of reflux, Conclusions. Adenocarcinomas in this animal model are not reflux-induced an d do not arise from the mucosa, Despite previous reports to the contrary, w e suggest that this model may not be valid for the study of reflux-induced esophageal adenocarcinoma. (C) 2000 Academic Press.