Gastric cancer has remained a serious burden worldwide, particularly in East Asian countries. However, nationwide prevention and screening programs for gastric cancer have not yet been established in most countries except in South Korea and Japan. Although evidence regarding the effectiveness of endoscopic screening for gastric cancer has been increasingly accumulated, such evidence remains weak because it is based on results from studies other than randomized controlled trials. Specifically, evidence was mostly based on the results of cohort and case-control studies mainly conducted in South Korea and Japan. However, the consistent positive results from these studies suggest promising evidence of mortality reduction from gastric cancer by endoscopic screening. The major harms of endoscopic screening include infection, adverse effects, false-positive results, and overdiagnosis. Despite the possible harms of endoscopic screening, information regarding these harms remains insufficient. To provide appropriate cancer screening, a balance of benefits and harms should always be considered when cancer screening is introduced as a public policy. Quality assurance is very important for the implementation of cancer screening to provide high-quality and safe screening and minimize harms. Endoscopic screening for gastric cancer has shown promising results, and thus deserves further evaluation to reliably establish its effectiveness and optimal use.
Keywords: Cancer screening; Case-control study; Cohort study; Gastric cancer; Harms; Mortality reduction; Upper gastrointestinal endoscopy.