Endoscopy appears to be more sensitive than photofluorography for the detection of gastric cancer. Time-trend analysis and case-control studies of gastric endoscopy suggest a twofold decrease in gastric cancer mortality in screened versus unscreened individuals;[24,25,26,27,28] however, this stands in contrast to studies of stronger design.
A cohort study of endoscopic screening was conducted in Linqu County, China, where gastric cancer rates are high, in which 4,394 adult residents aged 35 to 64 years were screened. Individuals were screened at an average of 4.5-year intervals, except for a high-risk subset (689 individuals) that was screened 2 years after the initial examination. Of the 85 cases of gastric cancer occurring in the cohort, 58 were detected with screening. No impact on gastric cancer mortality was observed among screened individuals. The standardized mortality ratio (SMR) for gastric cancer 10 years after the initial screen was 1.01 (95% confidence interval, 0.72–1.37). The SMR for all-cause mortality was significantly lower among participants because individuals with hypertension, liver disease, and chronic obstructive pulmonary disease were not eligible to participate. The data were observational, and not primarily collected to evaluate the effect of screening on gastric cancer mortality. In addition, the intervals between screens may have been too long.
There are no studies evaluating the effect of screening with serum pepsinogen on gastric cancer mortality, and there are important limitations to its use as a screening test. Low serum pepsinogen levels indicate the presence of atrophic gastritis and are therefore applicable to the detection of presumed precursors for intestinal type gastric cancer rather than the diffuse type. In addition, there are no standard cut-off values of abnormality.[12,30] Finally, eradication of H. pylori and use of proton pump inhibitors for the management of indigestion change pepsinogen levels, making interpretation of results difficult in the setting of widespread use of these interventions.[12,20]
In Japan, measurement of serum pepsinogen levels I and II (PGI and PGII) in 5,113 subjects also screened by endoscopy (13 gastric cancers detected), used cut-off points for identifying risk for gastric cancer of less than 70 ng/mL for PGI and less than 3 ng/mL for the PGI:PGII ratio. This combination provided a sensitivity of 84.6%, a specificity of 73.5%, a PPV of 0.81%, and a negative predictive value of 99.6%.
Clinical considerations for high risk groups
There may be justification for screening some populations of Americans at higher risk, although there is considerable discussion about how much incidence would make the examination worthwhile. Potential subgroups might include elderly patients with atrophic gastritis or pernicious anemia, patients with partial gastrectomy, patients with the diagnosis of sporadic adenomas, familial adenomatous polyposis, or hereditary nonpolyposis colon cancer, and immigrant ethnic populations from countries with high rates of gastric carcinoma.[9,10]