Impact of Helicobacter pylori Infection on Gastric Cancer Incidence in a General Japanese Population

Abstract

SINCE THE discovery of Helicobacter pylori in 1983, much research has focused on the relationship of this bacterium to gastric cancer. A number of clinical case-control studies have found positive associations between H pylori infection and gastric cancer.¹ In addition, 8 prospective, nested case-control studies on this issue have since been reported.^2-9 Of these nested case-control studies, five^2-4,8,9 have shown a significant association between IgG seropositivity for H pylori and gastric cancer, and one⁷ has shown that the risk of gastric cancer was significantly increased among subjects showing positive IgA antibodies against H pylori, but not among those showing positive IgG antibodies. Another 2 studies from Asian countries^5,6 have failed to reveal a significant relationship between IgG seropositivity and gastric cancer. Since all previous studies were of cross-sectional or nested case-control design, the possibility of selection bias could not be ruled out, and the impact of H pylori infection on the development of gastric cancer in a general population could not be fully evaluated. Further, a number of additional factors that might influence gastric cancer, such as smoking habits, alcohol intake, history of peptic ulcer disease, and dietary factors,^10-14 should be taken into account when the H pylori–cancer association is assessed.