Barrett's esophagus: an overview of the molecular biology.

The significance of specialized intestinal metaplasia in the esophagus is its associated risk with esophageal adenocarcinoma. This tumor has increased in incidence by over 70% in 20 years. Specialized intestinal metaplasia is the most important risk factor for adenocarcinoma of the esophagus and has been reported in 9-32% of unselected patients in general endoscopy units. The annual risk of esophageal adenocarcinoma for patients with specialized intestinal metaplasia is thought to be approximately 1%, at least 30 times that of the general population. Those with long segments of specialized intestinal metaplasia are thought to be at the greatest risk. Both environmental and molecular changes have been identified in the transition from squamous epithelium through specialized intestinal metaplasia to esophageal adenocarcinoma. The most important molecular changes include impaired regulation of the cell cycle, altered function of known oncogenes and tumor-suppressor genes, changes in cell adhesion molecules, and aneuploidy. This has given rise to a metaplasia/dysplasia/carcinoma model for the evolution of esophageal carcinoma.