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Screening and Surveillance
The majority of the literature regarding screening for gastric cancer comes from east Asia, where the prevalence of this disease is among the highest in the world.236 Since 1960, the Japanese have been performing mass screening using upper GI barium studies followed by endoscopy if any suspicious lesions are found, and this continues to represent the recommended approach based on current Japanese cancer screening guidelines.237 Japanese researchers have reported a sensitivity of 66% to 90% and a specificity of 77% to 90% for this screening method.238 However, survey studies have shown that, in clinical practice, upper endoscopy is the most widely employed screening test for gastric cancer in Asia.239
Not surprisingly, studies from Japan have also shown that screening results in diagnosis of gastric cancer at earlier stages, with 1 study reporting more than half of screened cases diagnosed as stage I.240Long-term follow-up data from the Japanese Public Health Center cohort showed that subjects who underwent screening had a nearly 50% reduced risk of death from gastric cancer.241 A separate cohort study from Japan found a 25% to 35% risk reduction in death from gastric cancer among those who participated in gastric cancer screening.242 However, similar risk reductions were seen for death from all causes, casting a level of uncertainty on the true magnitude of benefit associated with screening with respect to preventing death from gastric cancer.
The serum pepsinogen (PG) test is increasingly used to screen for patients at highest risk for having preneoplastic gastric lesions.243The stomach produces 2 types of pepsinogens: PGI and PGII. In chronic atrophic gastritis, production of PGI is reduced, whereas PGII levels remain relatively constant (see Chapter 52). Therefore, both low serum PGI levels (<70 mg/L) and a low PGI/II ratio (<3.0) are useful for the identification of patients with atrophic gastritis.236 Large prospective cohort studies have shown that baseline PGI, PGI/II, and Hp antibody levels combined can successfully identify patients at highest risk for developing gastric cancer.244,245
Screening with upper endoscopy is likely cost-effective in moderate- to high-risk populations, such as older Asian men.246 However, in populations with a lower incidence of gastric cancer, screening is less likely to have the same degree of beneficial impact. In the USA, there are currently no practice guidelines with regard to surveillance of patients incidentally found to have intestinal metaplasia of the stomach. However, results of a recent decision analysis suggested that surveillance of patients with intestinal metaplasia without dysplasia is extremely cost-ineffective.247