Barrett’s esophagus is a pre-cancerous condition of the esophagus characterized by the abnormal presence of columnar epithelium in the surface lining of the lower esophagus. Typically the surface lining of the lower esophagus should only contain squamous cells; however reflux of stomach contents, especially acid, into the esophagus causes these squamous cells to be replaced by columnar epithelial cells more similar to those found in the stomach and intestines. This abnormal epithelium is prone to develop pre-cancerous, or pre-malignant, changes called dsyplasia, which is a term for abnormalities in cells that do not appear normal under the microscope, but are not yet characteristic of invasive cancer. Recent evidence suggests that adenocarcinoma of the esophagus may arise from Barrett’s esophagus.
Approximately 1-2% of the adult population have Barrett’s esophagus. Patients with known Barrett’s esophagus should be considered for screening programs for the detection of dysplasia or cancer. The goal of screening is to detect cancer early when it can be cured with surgery. Screening typically requires endoscopic examination with routine biopsies every six months to two years. In one clinical study, approximately 3% of patients with Barrett’s esophagus developed adenocarcinoma, with the earliest discovered 4 years after initiation of surveillance. Twenty percent of patients developed low-grade dysplasia and 4% developed high-grade dysplasia. This study suggested that surveillance endoscopy could be delayed safely for two years after the initial biopsy if negative for dysplasia.
Treatment of patients with Barrett’s esophagus depends on what is seen under the microscope from tissue obtained by endoscopic biopsy. In patients with Barrett’s esophagus without dysplasia, attempts are made to prevent reflux and/or to eradicate the columnar epithelium in order to encourage squamous epithelium to grow. In patients with low-grade dysplasia, there have been attempts to halt the progression to high-grade dysplasia. In patients with high-grade dysplasia, the usual treatment is esophagectomy because of the high incidence of invasive cancer that is present but not found on endoscopic biopsy and the high cure rate of surgery. Patients with low-grade dysplasia do not develop invasive cancer without progressing to high-grade dysplasia first.
There have been many attempts to treat the reflux associated with Barrett’s esophagus in hope of preventing dysplasia, which leads to adenocarcinoma. These treatments have ranged from intensive antacid therapy to surgical procedures to correct reflux. There is very little evidence that intensive antacid therapy prevents progression to dysplasia or controls reflux. However, there is evidence that surgical correction of reflux may be of benefit both in reducing symptoms and possibly in reducing the extent of Barrett’s esophagus and the evolution to dysplasia.
In order to eradicate the columnar epithelium associated with Barrett’s esophagus and replace it with normal squamous cells, researchers have evaluated techniques such as photodynamic laser treatments and various methods of delivering high heat to coagulate abnormal cells. These treatments can decrease the amount of columnar epithelium present in a given segment of esophagus; however it is still unclear whether or not they prevent progression to dysplasia and ultimately to cancer. The results of one study indicated that photodynamic treatment converted 75-80% of columnar epithelium to squamous epithelium, with complete elimination of columnar epithelium in approximately half of the patients.
Anti-reflux surgery may prevent or reverse the development of low-grade dysplasia associated with Barrett’s esophagus.
In addition, researchers have evaluated techniques, such as photodynamic treatments with a laser and the delivery of heat to coagulate cells, in an effort to eradicate low-grade dysplasia. The results of one study indicated that photodynamic treatment eliminated mucosal dysplasia in most patients. Many of these treatments have an effect on Barrett’s esophagus and low-grade dysplasia; however it is still unclear whether or not these treatments consistently prevent progression to high-grade dysplasia and cancer.
The treatment of choice for patients with Barrett’s esophagus that has progressed to high-grade dysplasia is esophagectomy, since the progression to invasive cancer in patients with high-grade dysplasia approaches 50%. Patients with Barrett’s esophagus with high-grade dysplasia who are treated with early surgery may have a better chance of a cure than patients who wait until the biopsy shows invasive cancer. However, it is important to have the diagnosis of high-grade dysplasia confirmed by at least two pathologists since this is a difficult diagnosis to make and removal of the esophagus is major surgery. The cure rate following an esophagectomy for patients with high-grade dysplasia is over 90%, while the cure rate for patients who have adenocarcinoma will depend on the stage at diagnosis.
Since some patients with high-grade dysplasia will not be well enough to undergo esophagectomy, other treatments such as photodynamic laser treatments and various forms of delivering heat can be utilized to kill the dysplastic cells. While these treatments have a significant effect on high-grade dysplasia, it is still unclear whether or not they prevent progression to cancer. The results of one clinical study indicate that photodynamic laser treatment eliminated mucosal dysplasia in most patients, but the long-term effects of such treatment are unknown. For patients who cannot undergo surgery, photodynamic laser treatment may be acceptable in selected patients.
Reversal Therapy: Since Barrett’s esophagus and associated dysplatic changes are limited to the surface lining of the esophagus, researchers continue to evaluate new methods to reverse these changes. All of these techniques are performed through an endoscope and include electrocoagulation, heater probe, argon plasma coagulation and photodynamic laser treatments. Long-term studies will be needed to see if any of these treatments prevent the development of cancer.