What is Barrett's esophagus?

The normal esophagus (swallowing tube) is lined by a pinkish-white tissue called squamous epithelium. Some people also have red stomach tissue (normal appearing columnar epithelium) present in the bottom part of the esophagus. Barrett's esophagus is a condition in which the normal squamous epithelium of the esophagus has been replaced by an abnormal red columnar epithelium called specialized intestinal metaplasia. Specialized intestinal metaplasia is red, like normal stomach tissue, but does not look like stomach tissue under the microscope. Therefore, a biopsy (a piece of tissue taken from the esophagus) is needed to diagnose Barrett's esophagus.

Normal esophagus and stomach		Inside the normal esophagus and stomach
The esophagus passes through a hole in the diaphragm (breathing muscle) where it joins the stomach. The entire stomach is within the abdominal cavity, below the diaphragm.		The entire esophagus is lined by normal squamous (shown here as light pink). The stomach is lined by normal columnar lining (shown here as dark pink). The region where the normal squamous esophageal lining joins the normal columnar stomach lining is called the squamocolumnar junction.

The Barrett's lining always begins at the bottom of the esophagus where the esophagus joins the stomach and extends upward toward the mouth for varying lengths. Some Barrett's linings are short, less than 3 cm (1.3 inches) in length, and some are long (3 cm or greater in length).

Hiatal hernia

Most people with Barrett's esophagus have a hiatal hernia. However, hiatal hernias are very common and most people who have a hiatal hernia do not have Barrett's esophagus.

Hiatal hernia

The diaphragm (breathing muscle) separates the abdominal cavity from the chest cavity. Normally the entire stomach lies within the abdominal cavity. In this illustration, a small portion of the stomach has moved backwards through the opening in the diaphragm and into the chest cavity. This small portion of stomach above the diaphragm is referred to as a hiatal hernia.

Inside the normal esophagus with hiatal hernia	Inside a short segment Barrett's esophagus	Inside a long segment Barrett's esophagus
The entire esophagus is lined by normal squamous (shown here as light pink). The stomach is lined by normal columnar lining (shown here as dark pink). The region where the normal squamous esophageal lining joins the normal columnar stomach lining is called the squamocolumnar junction. In this case, the squamocolumnar junction has moved up and away from the diaphragm because of the hiatal hernia.	A short length of Barrett's esophagus is seen between the top of the hiatal hernia and the normal squamous esophagus. In this case, the squamocolumnar junction is made up of normal squamous esophageal lining on one side and Barrett's esophagus (specialized intestinal metaplasia) on the other side. The Barrett's esophagus must be confirmed by biopsy.	A long length of Barrett's esophagus is seen between the top of the hiatal hernia and the normal squamous esophagus. The squamocolumnar junction has moved a great distance up and away from the diaphragm due to the long segment of Barrett's esophagus (specialized intestinal metaplasia). The Barrett's esophagus must be confirmed by biopsy.

Barrett's esophagus and cancer

Barrett's esophagus is a pre-malignant (precancerous) condition. This means that the Barrett's lining is more prone to developing cancer than other normal tissues of the body. The type of cancer that develops in Barrett's esophagus is called esophageal adenocarcinoma. Since the 1970's, this cancer has been rapidly increasing in Western Europe and the United States. Esophageal adenocarcinoma now accounts for 60% of all esophageal cancers in the U.S. with an estimated 8,000 new cases diagnosed per year.

People who have Barrett's esophagus have a 30 to 40 fold increased risk of developing esophageal adenocarcinoma as compared to the general population. Still, the overall cancer risk in patients who have Barrett's esophagus is low. The results of multiple studies of patients who are being followed by a doctor for their Barrett's esophagus indicate that most patients with Barrett's esophagus (90-95%) DO NOT develop cancer during long-term follow-up. In addition, autopsy studies have shown that most patients who have Barrett's esophagus live their lives without ever developing Barrett's associated cancer and die of other causes.

The changing definition of Barrett's esophagus

The definition of Barrett's esophagus has changed since the condition was first described in 1950 by the British surgeon, Norman Barrett. Dr. Barrett proposed that the red-colored esophagus seen in some patients was actually part of the stomach and that these patients were probably born with a short esophagus (due to the short length of the white squamous esophageal lining). Later, Barrett's esophagus was defined as any red esophageal lining (columnar epithelium), including normal stomach lining, of 3 cm or greater in length.

We now have evidence that most esophageal adenocarcinomas develop in an abnormal columnar lining in the esophagus called specialized intestinal metaplasia. There is little evidence, thus far, that esophageal adenocarcinomas develop in the columnar stomach lining that can sometimes be present in the esophagus. Both types of these columnar linings look red by upper endoscopy, a procedure performed by a gastrointestinal doctor to examine the esophagus. To confirm that a red lining in the esophagus is indeed specialized intestinal metaplasia, the doctor must take multiple biopsies to obtain pieces of tissue from the lining and send it to the pathology lab for histologic analysis (examination of the tissue under a microscope).

According to the American College of Gastroenterology guidelines, Barrett's esophagus should now be defined as "a change in the ESOPHAGEAL epithelium (lining) of ANY LENGTH that can be recognized at upper endoscopy and is confirmed to have intestinal metaplasia by biopsy." This definition makes the distinction between the stomach lining that can be present in the esophagus and the abnormal specialized intestinal metaplasia. The new definition also emphasizes that the intestinal metaplasia must be esophageal in location. Many patients have intestinal metaplasia at the very top of the stomach, just below where the esophagus ends (intestinal metaplasia of the gastric cardia). Intestinal metaplasia in this location is NOT classified as Barrett's esophagus. At the present time, because specialized intestinal metaplasia is the only lining known to have an increased risk of developing esophageal cancer, it is recommended that only patients who have specialized intestinal metaplasia of the esophagus need to undergo endoscopic biopsy surveillance (cancer surveillance procedure) to detect esophageal adenocarcinoma, if it develops, at an early and curable stage.