Background and aim: High-grade atypia demonstrated by endocytoscopy may be a key criterion for the diagnosis of gastric cancer. We therefore sought to verify whether endocytoscopic atypia can provide satisfactory levels of diagnostic accuracy and concordance among trainee and expert endoscopists.
Method: A total of 100 lesions evaluated by endocytoscopy and histopathology were enrolled to create an endocytoscopic image catalog (44 early cancers, 10 low-grade adenomas, 46 non-neoplastic lesions). Four endoscopists (two trainees and two experts) independently reviewed the catalog images and evaluated each of them for the presence or absence of endocytoscopic atypia. High-grade endocytoscopic atypia, as a criterion for cancer diagnosis, was defined as the consistent observation of any of the following features: lumen absence, lumen fusion, and irregular nuclei showing the three typical features (heterogeneous shape, swelling, and disarrangement).
Results: High-grade endocytoscopic atypia was observed in 78 %, 18 %, and 4 % of cancers, adenomas, and non-neoplastic lesions, respectively. The sensitivity, specificity, accuracy, and positive and negative predictive values for cancer diagnosis by endocytoscopy were 78.4 %, 93.3 %, 87.3 %, 85.4 %, and 87.3 %, respectively. The concordance rate for the results of high-grade endocytoscopic atypia was good among the four endoscopists (κ value 0.682). No significant difference in diagnostic accuracy or concordance was observed between trainee and expert endoscopists.
Conclusion: Using the defined high-grade atypia as a diagnostic criterion of cancer, endocytoscopy provided a satisfactory level of accuracy and concordance for the diagnosis of early gastric cancer, regardless of endoscopic expertise.
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