Is adenocarcinoma following esophagoduodenostomy without carcinogen in the rat reflux-induced?

BACKGROUND A widely used rat model for reflux-induced esophageal adenocarcinoma in the absence of carcinogens involves induction of duodenoesophageal reflux by performance of esophagoduodenostomy. The aim of this study was to test the hypothesis that acid reflux reduces the incidence of adenocarcinoma in this animal model. METHODS One hundred ninety 8-week-old male Sprague-Dawley rats were studied. The animals were randomly divided into four groups with a different type of reflux established in each group. Group 1 had an esophagoduodenostomy for duodenogastroesophageal reflux (n = 59), group 2 had an esophagoduodenostomy and a total gastrectomy for duodenoesophageal reflux (n = 54), group 3 had an esophagoduodenostomy and a total gastrectomy with acid supplementation 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 eliminate all reflux (n = 25). One hundred eighty-eight surviving animals were sacrificed at 36 weeks of age and the resected esophagi were examined. RESULTS All animals except the no reflux control group had severe reflux esophagitis. The frequency of tumor development was similar in all study groups. All of the tumors were well-differentiated adenocarcinomas that were located 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 evidence of columnar lining of the esophagus but an admixture of squamous and 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 and do not arise from the mucosa. Despite previous reports to the contrary, we suggest that this model may not be valid for the study of reflux-induced esophageal adenocarcinoma.