May 24, 2007 The use of concentrated radio waves appears to be a safe and effective way to "burn" away abnormal cell growth in the esophagus that can be a precursor of cancer.
The new procedure is being tested in patients with Barrett's esophagus, a condition associated with the continued reflux of stomach acids into the lower esophagus that can damage its lining over time. While this condition is relatively common, a small percentage of patients will go on to develop abnormal cell growth known as dysplasia, a condition that can lead to esophageal cancer.
Gastroenterologists at Duke University Medical Center found that delivering concentrated radio waves through a catheter inserted down the esophagus can effectively treat the dysplasia with fewer side effects than current treatment methods. After the treatment, known as radiofrequency ablation, the treated cells die, slough off and are replaced within four to six weeks by new, healthier cells.
In a review of the first 12 patients treated with radiofrequency ablation at Duke, gastroenterologist Darren Pavey, M.B.B.S., found that three months after treatment, 89 percent of patients had more normal-looking esophageal tissue when viewed with an endoscope inserted down the esophagus. When samples of the new cells were analyzed in the laboratory, half of the patients were shown to have healthier tissues.
"In the procedure, which takes about 20 to 30 minutes, we insert a catheter down the esophagus and superficially burn the layer of cells that are abnormal," Pavey said. "The procedure is performed on patients as an outpatient procedure under conscious sedation, much as during a colonoscopy. The patients find that they have little or no discomfort following the procedure."
Pavey said that if radiofrequency ablation is proven effective in larger trials now under way, physicians will be able to offer a technique that has fewer side effects and is better tolerated by patients.
There are currently two main treatments for Barrett's esophagus with high grade dysplasia. The surgical approach involves removing the affected portion of esophagus. It is a major operation that has up to a 6 percent mortality rate and also can leave patients with reflux and swallowing problems, Pavey said.
A second approach, in use for the past 10 years, is known as photodynamic therapy. It involves a photosensitizing agent that is preferentially taken up by abnormal cells. Physicians then shine a laser light into the esophagus, and the light kills the target cells. However, patients must avoid direct sunlight for several weeks, and up to 30 percent of patients experience scarring of the esophagus severe enough to affect swallowing.
"So far, radiofrequency ablation seems to be less invasive than surgery and better tolerated than photodynamic therapy," Pavey said. "This approach has the potential to dramatically alter the way we treat patients with Barrett's esophagus."
While the incidence of Barrett's esophagus is difficult to determine, studies at autopsy indicate that the condition occurs in one in every 60 to 80 people in the United States, mostly in Caucasians. It also occurs four times more frequently in men than women. About 10 percent of patients with long-term gastrointestinal reflux, or heartburn, will go on to develop Barrett's esophagus.
"In our study, we also found that radiofrequency ablation appears to be effective for those patients who have had an incomplete response following treatment with photodynamic therapy," Pavey said
Pavey presented the results of the analysis on Tuesday, May 22, at the annual Digestive Disease Week conference in Washington, D.C. His analysis was supported by Duke's Division of Gastroenterology.
Eighteen centers, including Duke, are currently enrolling patients in a clinical trial comparing the effectiveness of radiofrequency ablation to the current methods of treating patients with Barrett's esophagus. It is expected that 120 patients will be enrolled.
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