Review article: is there significant variation in the risk of gastric cancer associated with Helicobacter pylori infection?

Helicobacter pylori infection is a risk factor for gastric cancer and most epidemiological studies have estimated a relative risk associated with infection in the order of two to four-fold. There is interest in the extent to which this risk estimate might vary between different populations especially as several populations have been identified with low rates of gastric cancer despite a high infection prevalence. Methodological differences between studies make it difficult to compare the results of retrospective case-control studies to quantify the variation in risk, but prospective studies indicate that there may be a six-fold variation in risk between different populations. It is likely that genetic and/or environmental co-factors are important in modifying the risk associated with H. pylori infection but there are few studies that have fully investigated the role of such co-factors.