The role of alkaline reflux in esophageal carcinogenesis induced by N‐amyl‐N‐methylnitrosamine in rats

It is now accepted that the incidence of esophageal carcinoma is highest in the middle thoracic region. Esophageal carcinoma after gastrectomy, however, has a tendency to develop in the lower thoracic region. These studies suggest a possible correlation between the development of esophageal carcinoma and gastrectomy, i.e., alkaline reflux into the esophagus. To elucidate this correlation, the role of alkaline reflux of duodenal contents in the development of esophageal squamous‐cell carcinoma induced by N‐amyl‐N‐methylnitrosamine (AMN) was investigated in Wistar rats. The animals were divided into 3 groups; gastrectomized rats with or without regurgitation of duodenal contents into the esophagus, and control rats without gastrectomy. All received low doses of AMN for 8 weeks and were subsequently killed for pathological examination. Esophageal squamous‐cell carcinomas were found only in gastrectomized rats with regurgitation. The carcinomas were found exclusively in areas of reflux esophagitis and were accompanied by severe dysplasia. Our results indicate that alkaline reflux of duodenal contents strongly contributes to the development of esophageal squamous‐cell carcinoma.