[Critical review on the WHO/IARC report regarding carcinogenicity of Helicobacter pylori]

Helicobacter pylori has been defined as a "definite carcinogen" at the WHO/IARC meeting in 1994. H. pylori causes histological gastritis. Long-lasting infection may induce atrophic gastritis, which is considered to be the first step in the gastritis-metaplasia-carcinoma sequence of the stomach. In a pooled analysis of the three prospective epidemiological studies, the relative risk for developing gastric cancer with H. pylori infection was 3.8, which was statistically significant. Thus, it was concluded that there was sufficient evidence in humans for the carcinogenicity of infection with H. pylori. However, there was no evidence experimentally for the carcinogenicity of infection with H. pylori. Further study is necessary to elucidate the role of H. pylori in gastric carcinogenesis.