When duodenal content is allowed to reflux into the esophagus of nitrosamine-treated rats, esophageal cancer is induced more rapidly and at higher frequency than after carcinogen treatment alone. The purpose of the present study was to identify the components of the duodenal content that are responsible for enhancing esophageal carcinogenesis. Eight-week-old Sprague-Dawley rats underwent one of four operations as follows: diversion of bile alone, pancreatic juice alone, both bile and pancreatic juice into the esophagus, or a control operation with no induced reflux. Two weeks after surgery, rats were treated with the esophageal carcinogen 2,6-dimethylnitrosomorpholine (48 mg/kg [0.1 of LD50] intraperitoneally weekly for 20 weeks). The rats were killed at age 30 weeks. The esophagus was removed and full-length strips were examined under a microscope; separate segments were taken for flow cytometric evaluation. The prevalence of DNA aneuploidy and histologic esophageal papillomas or squamous cancer was increased in carcinogen-treated rats with pancreatic juice reflux (P <0.05 vs. control) and the combination of pancreatic and bile reflux (P <0.05 vs. control) but not in rats with bile reflux alone. We conclude that pancreatic juice is the most potent component of the duodenal refluxate in the promotion of esophageal carcinogenesis in rats.
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