Barrett's esophagus is a condition characterized by abnormal alterations in the cells that line the esophagus. A normal esophagus is lined with flat squamous cells, while in the case of Barrett's esophagus, these cells adopt a tall columnar shape that closely resembles that of the cells found in the linings of the intestines.
Sometimes called columnar-lined esophagus, the condition is diagnosed when these columnar cells are identified on endoscopy or microscopic analysis. The abnormal cells have an increased likelihood of becoming dysplasic over time and Barrett's esophagus is therefore considered a risk factor for esophageal cancer.
Barrett's esophagus occurs as a result of long-standing and severe gastro-esophageal reflux disease (GERD). When acid regurgitation has occurred over a long-term period, the lower end of the esophagus and its mucosal lining can become inflamed and irritated on exposure to the gastric acids. In a small proportion of people with long term GERD, the cells of the esophageal lining adopt the columnar shape of the intestinal cells.
In addition to GERD, a patient may also have had duodeno-gastro-esophageal reflux, which leads to reflux of the contents of the duodenum (first part of the small intestines) into the esophagus. In such cases, the lining of the esophagus is exposed to the corrosive and injurious effects of both the gastric acids and the bile present in the duodenum.
With repeated exposure to acids, the lower end of the esophagus becomes inflamed which can eventually induce esophageal stem cells to produce new cells in an attempt to repair the tissue and, over time, the cells lining the esophagus may change into columnar cells. The extent of this cell metaplasia depends on the duration and severity of exposure to the acids as well as on the nature of the cytokine response or inflammatory response to injury.
Research suggests that there is an association between Barret's esophagus and smoking cigarettes, and alcohol consumption is also thought to be a risk factor. In addition, both smoking and alcohol consumption are in fact risk factors for GERD. By contrast, Helicobacter pylori infection has been shown to be protective against the development of Barret's esophagus, as the infection leads to reduced gastric acidity, thereby reducing the likelihood and extent of GERD.