WebMD Medical News
Louise Chang, MD
May 20, 2008 -- A real-time microscopic technique could lead to earlier diagnosis and treatment of gastrointestinal disorders ranging from reflux disease to colon cancer, new studies suggest.
Called confocal laser endomicroscopy (CLE), the technique may also help to avoid unnecessary biopsies, researchers say.
CLE uses a tiny microscope at the end of an endoscope, a flexible, lighted instrument that is used to view the gastrointestinal tract. Three new studies of the technique were presented at Digestive Disease Week 2008 in San Diego.
"Images are magnified 1,000 times, so we can see microscopic changes throughout the GI tract that we can't see with traditional endoscopy," says Kerry B. Dunbar, MD, a fellow in the division of gastroenterology and hepatology at Johns Hopkins University School of Medicine in Baltimore.
"What that means is that we can detect suspicious activity, such as precancerous cells, immediately," Dunbar tells WebMD.
Without CLE, it can take days or even weeks to get a diagnosis "because we'd have to take photos and then do a biopsy and send it to a pathologist to interpret the results," says Pankaj J. Pasricha, MD, professor of medicine, gastroenterology and hepatology at Stanford University School of Medicine.
"CLE has the potential to revolutionize the field," says Pasricha, who moderated a news conference to discuss the findings.
In one study, Dunbar and colleagues performed 2,102 CLE examinations on 1,771 patients. The results were compared with those obtained using traditional endoscopy.
CLE rarely missed any suspicious lesions, Dunbar says. There were a few false positives, "where we thought we saw something on CLE and it turned out to be nothing," she says.
Overall, CLE had an accuracy rate of 91% in the upper GI tract and 93% in the lower GI tract.
Among the disorders diagnosed were acid reflux disease, Barrett's esophagus, esophageal cancer, colon cancer, gastritis, celiac disease, and inflammatory bowel disease.
In 20% of cases, the CLE results would have changed the diagnosis, Dunbar adds. "Most were cases where we saw signs of dysplasia (abnormal cell growth that is a precursor to cancer) that could not be seen on traditional endoscopy," she says.
The complication rate, chiefly nausea from a fluorescent yellow dye that is injected into patients so doctors can better visualize cells, was less than 1%.
"I do warn patients that they will be yellow for a few hours after the procedure, so they shouldn't plan on having their picture taken," she says.
In a second study, Dunbar and colleagues found that CLE may be able to reduce by 60% the number of biopsies in patients with Barrett's esophagus, a condition that can lead to esophageal cancer.
"Treating Barrett's is one of the great challenges as it can be very difficult to see [cancerous] changes with standard endoscopy," Dunbar says.
As a result, recommendations call for patients to come in every one to three years for random tissue biopsies, which are invasive and can cause bleeding.
The study involved 36 patients. Fifteen were referred by their doctors because of high-grade dysplasia. Twenty-one patients had previously diagnosed Barrett's esophagus and were coming in for their regular surveillance biopsy. All underwent standard endoscopy plus tissue biopsy as well as CLE.
"In the group with high-grade dysplasia that were really worried about, CLE found all the areas of dysplasia that the endoscope did, and we had to biopsy much less tissue," Dunbar says.
In the patients with previously diagnosed Barrett's esophagus, "CLE allowed investigators to take biopsies only of areas that looked suspicious, instead of performing many unnecessary random biopsies," she says.
Additionally, CLE "may allow us to detect and treat early cancers or high-grade dysplasia in Barrett's esophagus patients at the same visit," Dunbar says.
A third study found that CLE is highly accurate in distinguishing benign from precancerous polyps of the colon.
Researchers at the Mayo Clinic in Jacksonville studied about 50 people. All got CLE as well as a traditional colonoscopy with removal of any polyps.
Compared with the gold standard -- the pathologist's determination of whether a polyp was benign or cancerous -- CLE had an overall accuracy of 90%.
More importantly, CLE was able to identify small benign polyps that had virtually no chance of ever turning cancerous in 98% of cases, says researcher Michael Wallace, MD, a professor of medicine at Mayo.
"This is important because normally these polyps would be removed. With CLE, we can avoid removing benign polyps -- which is less expensive, more efficient, and safer," he tells WebMD.
There are two FDA-approved CLE scopes, according to Wallace: the Optiscan/Pentax and Mauna Kea Technologies' Cellvizio.
Dunbar says that so far, the procedure is available at few medical centers, such as Johns Hopkins, or for people enrolled in a clinical trial. But she thinks that will change as more people are trained and more sites purchase the equipment.
"It's slowly catching on," Dunbar says.
SOURCES:Digestive Disease Week 2008, San Diego, May 18-23,
2008.Kerry B. Dunbar, MD, fellow, division of gastroenterology and hepatology,
Johns Hopkins University School of Medicine, Baltimore.Pankaj J. Pasricha, MD, professor of medicine, gastroenterology and
hepatology, Stanford University School of Medicine, Stanford, Calif.Michael Wallace, MD, professor of medicine, Mayo Clinic, Jacksonville.
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