Conference Coverage

Imaging Combo May Diagnose Gastric Cancer Without Biopsy


 

FROM THE ANNUAL DIGESTIVE DISEASE WEEK

CHICAGO – The combination of white light endoscopy and magnifying narrow-band imaging shows promise for achieving accurate diagnosis of early gastric cancer, based on a prospective, randomized, controlled trial conducted in Japan.

"Magnifying narrow-band imaging improved [the] diagnostic performance of white light endoscopy for discriminating gastric cancer from benign small depressed lesions," said Dr. Noriya Uedo, the principal investigator. "Adding magnifying narrow-band imaging to white light endoscopy could make accurate diagnosis of early gastric cancer [possible] without biopsy."

Currently, a diagnosis is made primarily via biopsy, said Dr. Uedo at the annual Digestive Disease Week.

Narrow-band imaging (NBI) is a novel optical technology for examining the surface structure and vascular architecture in the superficial mucosa. "Using magnifying endoscopy, it enables us to evaluate detailed morphological features of both epithelium and vasculature corresponding to histology," he said.

This study was designed to compare the real-time diagnostic performance of conventional white light endoscopy vs. magnifying NBI for gastric lesions no larger than 1 cm.

The trial included patients with a history of endoscopic treatment of early gastric cancer who were at high risk for developing recurrent gastric cancer. The study’s primary objective was to contrast the diagnostic accuracy of the two modalities.

On enrollment, patients were screened with white light endoscopy, and those who were found to have a previously undiagnosed small depressed lesion were randomized to either the white light group or the magnifying NBI group. In the white light group, after the endoscopic finding was documented, the lesion was then evaluated with magnifying NBI.

Between June 2008 and May 2010, 1,365 patients were enrolled, and 362 were found to have small depressed lesions. These patients were randomized to the white light endoscopy group or the magnifying narrow-band imaging group. There were 20 patients with gastric carcinoma in each group.

The diagnostic accuracy of white light endoscopy was 65% (114 of 176), whereas that of magnifying NBI was 90% (160 of 177), and this difference was statistically significant (P less than .001). Sensitivity was also higher in the magnifying NBI group at 60% (12 of 20) vs. 40% (8 of 20), but this difference did not reach statistical significance. Specificity was significantly higher in the magnifying NBI group at 94% (148 of 157), compared with the white light endoscopy group at 68% (106 of 156; P less than .001).

The time required to make a diagnosis with magnifying NBI was about 30 seconds longer than with white light endoscopy. "The difference would be acceptable in a clinical setting, instead of taking a biopsy, I think," said Dr. Uedo of the department of gastrointestinal oncology, Osaka (Japan) Medical Center for Cancer and Cardiovascular Diseases.

The diagnostic performance of magnifying NBI following white light imaging, compared with white light imaging alone, was significantly better in terms of accuracy, sensitivity, and specificity (P less than .001 in each case).

Dr. Uedo said that the specificity of white light endoscopy was not very high, and the number of false-positive lesions was large. "So, the number of biopsies is also large," he said. Only 40% of carcinomas were correctly diagnosed based on their endoscopic appearance. However, he said, the number of false-positive lesions in the magnifying NBI group was small, because of the higher specificity, and in turn the number of biopsies was lower.

As for the combination of the two modalities, he said that it "shows extremely excellent performance for differentiation of carcinoma from [a] benign depressed lesion."

Gastric cancer is the second leading cause of cancer death worldwide, and the earlier the diagnosis, the better the patient’s prognosis.

The study was funded by a grant-in-aid for cancer research from the Ministry of Health, Labor, and Welfare of Japan. Dr. Uedo does not have any relevant financial or other relationship with any manufacturer or provider of commercial products or services discussed during the presentation.

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