Helicobacter pylori and gastric cardia cancer: What do we know about their relationship?

The incidence of gastric cardia cancer is increasing around the world. Since the discovery of Helicobacter pylori(H. pylori), numerous studies have proved that it is a causative factor for many kinds of digestive system tumors. Although the literature on gastric cardia cancer and H. pylori is not scarce, there are still many controversies on the relationship between gastric cardia cancer and H. pylori.Many Western research results showed that there was a negative or no correlation between H. pylori infection and gastric cardia cancer, but in several studies in Asian countries, such as China, H. pylori was demonstrated to be a risk factor for gastric cardia cancer. Therefore, we intended to analyze the related studies to find out the relationship between H. pylori and gastric cardia cancer and find out the causes of the above controversies. We also conducted a metaanalysis of the relationship between cag A positive expression of H. pylori and gastric cardia cancer, to find out whether there is an effect between those two.The primary purpose of this paper was to explore the relationship between gastric cardia cancer and H. pylori. Through analysis, the study showed the reasons for the controversies mentioned above:(1) Geographical factors could affect the relationship between H. pylori and gastric cardia cancer;(2) The definition of gastric cardia cancer in various studies is inconsistent. The result of a meta-analysis about the relationship between H. pylori virulence factor cag A and gastric cardia cancer showed that there was no relationship between these two.