Background & Aim: Early-stage gastric cancer (EGC) found after H. pylori eradication often has non-tumorous epithelium on the tumorous tissue and/or surface differentiation of tumors, which may confuse endoscopic and histologic diagnosis. We investigated the diagnostic reliability of EGC using conventional white light endoscopy (WLE), chromoendoscopy (CE) using indigo carmine, and magnifying endoscopy with narrow band imaging (ME-NBI) in patients with EGC with or without history of prior H. pylori eradication therapy. Methods: Diagnostic reliability of EGC by using the WLE, CE and ME-NBI was investigated in 71 EGC lesions diagnosed after successful H. pylori eradication (eradication group) and 115 EGC lesions with current H. pylori infection (control group). Results: Diagnostic reliability of EGC was lower in the eradication group than in the control group using all three modalities. In particular, the diagnostic accuracy of CE in the eradication group was especially lower compared to that of the control group (WLE: 74.6% vs. 86.1%, P=0.05; CE: 64.8% vs. 91.3%, P<0.0001; ME-NBI: 88.7% vs. 98.2%, P=0.01). The ME-NBI scored better in comparison with WLE and CE in the eradication group (both P<0.05). The indistinct EGC lesions in the eradicated group by using CE were associated with the presence of histological changes such as non-tumorous epithelium on the tumor and/or surface differentiation of tumors (P=0.005). Conclusions: It should be noted that the diagnostic reliability of EGC after H. pylori eradication becomes lower especially using CE. Indistinguishable cases using CE are associated with histological findings such as non-tumorous epithelium on the tumor and/or surface differentiation of tumors.
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