Proton pump inhibitors and gastric cancer: association is not causation

We read the article by Cheung et al 1 with interest. The research question whether there is a dose-related association between proton pump inhibitors (PPIs) and gastric cancer in a country where this malignancy is highly prevalent is an important one. They report that long-term PPI therapy is associated with an increased risk of gastric cancer in patients who have received Helicobacter pylori eradication therapy. The data suggest that patients taking PPI less than once per day had a lower risk of gastric cancer than did those taking PPIs at least daily, which would support there may be a dose-related response. There are many concerns that were not adequately addressed in the paper. The paper claims that all the subjects became H. pylori negative as they had all been prescribed eradication therapy and none had received subsequent therapy. However, no data on proof of cure were provided. There …