A study investigated the association between long-term use of proton pump inhibitors (PPIs, more than 1 year) and the risk of non-cardiac gastric adenocarcinoma in five Nordic countries.[2][1] It included 17,232 cases of patients with this cancer and 172,297 control subjects.[2] Long-term PPI use was present in 10.2% of cases (1766 patients) and 9.5% of controls (16312 subjects).[2][1] No association was found: the adjusted odds ratio was 1.01 (95% confidence interval 0.96–1.07).[2][1] The same result was true for long-term use of H2 receptor antagonists (aOR 1.03; 95% CI 0.86–1.23).[2][1] The authors identified errors in previous studies, such as PPI use shortly before diagnosis, short-term use, cardiac adenocarcinoma, and failure to consider Helicobacter pylori.[2][1] This is an observational study that does not confirm a causal relationship.[1][2]