Barrett's Esophagus (cont.)
Bhupinder Anand, MD
Wilfred M. Weinstein, MD
In this Article
Why is there so much interest in Barrett's esophagus?
The reason for the great interest in Barrett's esophagus is that it is associated with an increased risk of cancer of the esophagus. The type of cancer that occurs in patients with Barrett's is adenocarcinoma, which arises from the metaplastic intestinal tissue. The usual cancer of the esophagus that is not associated with Barrett's is squamous carcinoma, which arises from the squamous cells lining that is normally present in the esophagus. The connection between adenocarcinoma of the esophagus and Barrett's esophagus is now clear, and adenocarcinoma of the esophagus is increasing in frequency in most countries in the Western hemisphere.
The good news, however, is that the cancer occurs in relatively few patients with Barrett's esophagus. Still, the main challenge in this condition is to watch for early warning signs of cancer by taking biopsies at regular intervals during endoscopy. This practice is called surveillance and is similar, in principle, to the surveillance in women for cancer of the cervix, wherein PAP smears are taken at regular intervals.
What causes Barrett's esophagus?
Gastroesophageal reflux disease (GERD)
GERD causes Barrett's esophagus. The esophagus is a muscular tube that is located in the chest and serves to transfer food from the mouth to the stomach. The lower esophageal sphincter (LES) is a valve that is located at the junction of the stomach with the esophagus . Its function is to prevent acid and other contents of the stomach from coming back into the esophagus. GERD is a condition in which excessive acid-containing fluid refluxes (flows) back into the esophagus, in part because the lower esophageal sphincter is weak. The weakness of the LES may be related, in part, to the fact that virtually all GERD patients have hiatal hernia. In hiatal hernia, the upper few centimeters of the stomach slides back and forth between the abdomen and the chest through the diaphragm. This sliding may interfere with how the sphincter works as a barrier to reflux from the stomach to the esophagus.
Previously, the term hernia was used instead of GERD in explaining to patients the basis of their symptoms (usually heartburn) because virtually all GERD patients have hiatal hernias. GERD, however, is the more accurate term. Hiatal hernias are extremely common in the population and yet only a small number of people with hiatal hernia develop GERD. In other words, the presence of a hiatal hernia does not mean that the person will develop GERD. On the flip side, however, if a person has GERD, hiatal hernia is almost always present.
Thus, Barrett's esophagus is caused by chronic (of many years duration) and usually severe acid reflux. In some patients with GERD, the esophagus reacts to the repeated injury from the acidic fluid by changing the type of cells lining it from squamous (normal cells) to columnar (intestinal-type cells). This transformation, called metaplasia, is believed to be a protective response because the specialized columnar epithelium (epithelium means lining) in Barrett's esophagus is more resistant to injury from acid than the squamous epithelium.
Picture of gastroesophageal reflux disease (GERD)
Other contributors to Barrett's esophagus
The fluid in the stomach contains acid that is produced by the stomach. In addition, however, the fluid may contain bile acids (from bile produced by the liver) and enzymes (produced by the pancreas) that have refluxed back from the duodenum into the stomach. (The duodenum is the first part of the small intestine just beyond the stomach.) The acid that refluxes from the stomach to the esophagus is injurious to the esophagus. There is some evidence, however, that the bile and pancreatic enzymes combined with the acid may be more injurious than acid alone.
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