An Ecological Study on the Risk of Gastric Cancer With Helicobacter Pylori Prevalence and Other Potential Cofactors in Korea

Background: Korea has a high incidence of gastric cancer and a high prevalence of Helicobacter pylori infection. Observation of prevalence trends and determination of risk factors for gastric cancer are important to establish health policies to prevent and reduce the burden of disease. Currently, there is no evidence of complete correlation between prevalence of H. pylori infection and the occurrence of gastric cancer. Several explanations have been proposed for the paradox of high prevalence of infection and low gastric cancer incidence in certain places, including diet and salt consumption, genetic susceptibility, other infections, aflatoxin-contaminated food, and the interaction of all these factors, but none of them has been clearly established. Aim: To explore the potential effects of prevalence of H. pylori infection and other risk factors on gastric cancer incidence in Korea. Methods: Information on gastric cancer incidence, prevalence of H. pylori infection, and the risk factors for gastric cancer were evaluated from nationally representative data - the Korean National Cancer Registry, nationwide routine health check-up surveillance system, and National Health and Nutrition Survey, respectively. Secular trends of H. pylori infection prevalence and age-standardized incidence rates for gastric cancer by region were examined. Furthermore, trends of income level, education level, marital status, number of family members, smoking status, drinking status, obesity, diabetes, hypertension, dyslipidemia, and age-standardized incidence rates for gastric cancer by region were examined. Results: Gastric cancer incidence showed a decreasing trend from 2011 to 2015; 50.6%–44.4% for men and 22.1%–17.0% for women. The prevalence of H. pylori infection also showed a decreasing trend; from 66.9% in 1998%–54.4% in 2011. In Korea, areas with high prevalence of H. pylori infection also showed high gastric cancer incidence. However, the Chungcheong area showed relatively low prevalence of H. pylori infection, but had the highest gastric cancer incidence in Korea. Other factors which showed similar effects on gastric cancer incidence, like H. pylori infection were large family size (4 or more family members), low income, low education, and obesity. The effect of introduction of 'National Cancer Screening Program' will be evaluated in the final outcome. Conclusion: The results of this study indicated that significant regional differences exist between trends in H. pylori infection prevalence and gastric cancer incidence in Korea. Also, the possibility of lack of association between H. pylori prevalence and the incidence of gastric cancer are suggested. Overall, this study suggests the need for further research to explore potential factors accounting for regional differences in gastric cancer incidence in Korea.