Evaluation of serum markers for gastric cancer and its precursor diseases among high incidence and mortality rate of gastric cancer area.

Background: Mongolia has the highest mortality rate of gastric cancer. The early detection of cancer and down-staging screening for high risk patients are essential. Therefore, we aimed to validate serum markers for stratifying patients for further management.
Methods: Endoscopy and histological examination were performed to determine high risk and gastric cancer patients. Rapid urease test, culture and histological tests were performed to diagnose Helicobacter pylori infection. Serum pepsinogen (PG) I and II and anti-H. pylori IgG were measured by ELISA. Receiver Operating Characteristic analysis was used to extract the best cut-off point.
Results: Totally 752 non-cancer and 50 consecutive gastric cancer patients were involved. The corpus chronic gastritis (72%: 36/50 vs. 56.4%: 427/752), corpus atrophy (42.0%: 21/50 vs. 18.2%: 137/752) and intestinal metaplasia (IM) (64.0%: 32/50 vs. 21.5%: 162/752) were significantly higher in gastric cancer than non-cancer patients, respectively. Therefore, corpus chronic gastritis, corpus atrophy and IM were considered as high risk disease. The best serum marker to predict the high risk status was PGI/II < 3.1 (sensitivity 67.2%, specificity 61%) and PGI/II further reduced to < 2.2 (sensitivity 66%, specificity 65.1%) together with PGI < 28 ng/mL (sensitivity 70%, specificity 70%) were the best prediction for gastric cancer. The best cut-off point to diagnose H. pylori infection was anti-H. pylori IgG > 8 U/mL. Multivariate analysis showed that anti-H. pylori IgG > 8 U/mL and PGI/II < 3.1 increased risk for high risk status and PGI/II < 3.1 remained to increase risk for gastric cancer.
Conclusion: The serum diagnosis using PGI/II < 3.1 cut-off value is valuable marker to predict high risk patients for population based massive screening.