In North America, the character of esophageal carcinoma is changing. In most centers, adenocarcinoma of the esophagus is the predominant cell type and Barrett's esophagus is seen in many of these patients. Although this metaplastic transformation appears to be a major factor in the changing epidemiology of esophageal carcinoma, it is not the sole explanation for this shift from squamous cell carcinoma to adenocarcinoma.