3 - Esophageal carcinogenesis

Summary

High-risk diseases

A number of diseases, not only those directly affecting the esophagus, are associated with an increased risk of esophageal cancer. These diseases (Table 3.1) include chronic esophagitis, stricture, certain motility diseases, reflex esophagitis, Barrett's esophagus, Plummer–Vinson syndrome, celiac diseases, and tylosis. Chronic esophagitis is sometimes considered to be an essential precursor lesion for esophageal cancer in man, and is more conveniently discussed in the following section where the precursor lesions are considered.

High-risk diseases are a useful guide to the etiology of esophageal cancer. These diseases may have the same initial cause as cancer of the esophagus, but develop independently from it and for different reasons. Thus iron deficiency may be a contributing cause to esophageal cancer, as well as causing the anemia associated with Plummer–Vinson syndrome. Alternatively, the high-risk disease may obstruct the flow of food and drink through the esophagus and thus increase its vulnerability to carcinogens, as in the case of achalasia. Finally, a combination of mechanisms may be operative, as when gastro-esophageal reflux develops. In this case, smoking and alcohol consumption together are sufficient to cause esophageal cancer, but in addition they may provoke reflux, and then damage to the esophagus caused by contact with irritant stomach contents enhances the direct action of the carcinogens.