Risk of Gastric Cancer among Long-Term Proton Pump Inhibitor Users: a Population-Based Cohort Study.

To elucidate whether long-term proton pump inhibitor (PPI) users have an increased gastric cancer (GC) risk. We searched the 2009–2019 Korean National Health Insurance Services Database for patients aged > 40 years who claimed for Helicobacter pylori eradication (HPE) during 2009–2014. The GC incidence following a PPI exposure of > 180 cumulative defined daily dose (cDDD) and that following an exposure of < 180 cDDD were compared. The outcome was GC development at least 1 year following HPE. A propensity score (PS)–matched dataset was used for analysis within the same quartiles of the follow-up duration. Additionally, dose–response associations were assessed, and the mortality rates were compared between long-term PPI users and non-users. After PS matching, 144,091 pairs of PPI users and non-users were analyzed. During a median follow-up of 8.3 (interquartile range, 6.8–9.6) years, 1053 and 948 GC cases in PPI users and non-users, respectively, were identified, with the GC incidence (95