Screening of gastric cancer: who, when, and how.

Gastric cancer (GC) remains the leading cause of cancer mortality worldwide. Conceivably, early diagnosis may be achievable through screening of the high-risk population. Therefore, it is important to identify individuals harboring premalignant lesions that include atrophic gastritis, intestinal metaplasia, and mucosal dysplasia. The age threshold for GC screening depends on the regional incidence and the individual risk. In high-incidence countries such as Japan and Korea, the age to screen GC may be as early as 40 years. The mass screening by endoscopy in these countries would be able to detect a substantial portion of patients with early GCs as well as precancerous lesions. For the purpose of eliminating GC, however, these screening programs should be conducted in conjunction with Helicobacter pylori eradication. In low-incidence countries, it seems feasible to adopt a stepwise approach to identify high-risk individuals at first. The initial screening should focus on epidemiologic factors, genetic or hereditary risks, and the status of H pylori infection. Measurement of serum pepsinogen I and II and gastrin may detect atrophic gastritis in a noninvasive manner. Patients with these premalignant lesions should then receive endoscopic examination and enter surveillance. To date, there is no cost-effective strategy for an average-risk individual from a population with low incidence of GC, and therefore screening is unwarranted and cannot be recommended for them.