Randomized controlled trial of the second generation Narrow Band Imaging compared with White Light Imaging for detection of early gastric cancer

INTERVENTION: NBI followed by WLI WLI followed by NBI CONDITION: Early gastric cancer PRIMARY OUTCOME: Proportion of patients whose early gastric cancer is detected newly by non‐magnifying endoscopy SECONDARY OUTCOME: (1)Positive predictive value of non‐magnifying endoscopy; (2)Sensitivity and specificity of non‐magnifying endoscopy; (3)Examination time; (4)Assessment of lesions which are overlooked; (5)The number of biopsies which are needed to diagnose gastric cancer; (6)Sensitivity and specificity of Near‐focus mode; (7)Proportion of adverse events INCLUSION CRITERIA: Patients who plan to undergo upper gastrointestinal endoscopy and who meet one of following (1)‐(5) (1)Patients who have history of the endoscopic resection for early gastric cancer or adenoma (2)Patients whose endoscopy is performed for the present gastric cancer or adenoma (3)Patients who have history of the endoscopic resection for early esophageal cancer (4)Patients whose endoscopy is performed for the present esophageal cancer (5)Patients who have history of chemotherapy or radiotherapy for esophageal cancer