The aim of this article is to demonstrate the basic principles for the endoscopic diagnosis of early gastric cancer. The diagnostic process can be divided into two steps, detection and characterization. Detection requires good endoscopic technique, and thorough knowledge. With regard to technique, we should administer the optimum preparation to patients, including an antiperistaltic agent. Furthermore, in order to map the entire stomach we need to follow a standardized protocol, and we propose a systematic screening protocol for the stomach. With regard to knowledge, we should be able to identify high-risk background mucosa, and we should be aware of the indicators of a suspicious lesion. Chromoendoscopy and magnifying endoscopy are promising image-enhanced endoscopic techniques for characterization. The proposed criteria for a cancerous lesion are as follows: conventional endoscopic findings of 1) a well-demarcated lesion and 2) irregularity in color/surface pattern; vessel plus surface classification using magnifying endoscopy with narrow-band imaging findings of 1) irregular microvascular pattern with a demarcation line or 2) irregular microsurface pattern with a demarcation line. Conventional endoscopy and subsequent image-enhanced endoscopy can both contribute to the detection of early gastric cancer.
Keywords: Early gastric cancer; endoscopy; image-enhanced endoscopy; magnifying endoscopy with narrow-band imaging; systematic screening of the stomach.