Duration of use of proton pump inhibitors and the risk of gastric and oesophageal cancer

Background: There is increasing interest in the potential association between proton pump inhibitors (PPIs) and the risk of gastric and oesophageal cancer, yet the effect of duration of treatment needs clarification. Methods: This Swedish population-based cohort study assessed the influence of time since initiation of PPI treatment on the risk of gastric and oesophageal cancer, presented as standardised incidence ratios and 95% confidence intervals. Results: The risk of gastric and oesophageal cancer during the first year was 7-10 times higher than the background population, and remained 24-202% increased without any decrease over time after the first year. Conclusion: PPI use was associated with an increased risk of gastric and oesophageal cancer and the risk remained increased over follow-up. These results support our original hypothesis that use of PPIs may be a risk factor for gastric and oesophageal cancer in the general population of maintenance users, independent of underlying indications.