Antipsychotic use is inversely associated with gastric cancer risk: A nationwide population‐based nested case‐control study

OBJECTIVE: The association between antipsychotic use and gastric cancer risk remains unclear. Therefore, this study aimed to determine the association between antipsychotic exposure and the incidence of gastric cancer. METHODS: Using a nested case‐control design, a total of 34 470 gastric cancer patients and 163 430 nongastric cancer controls were identified from Taiwan's National Health Insurance Research Database between 1 January 1997 and 31 December 2013. We analyzed the data using a conditional logistic regression model to adjust for possible confounding variables. RESULTS: Antipsychotic use was independently inversely associated with gastric cancer risk after controlling for potential confounding factors including income, urbanization, medications, physical and medical illness, aspirin use, nonsteroidal anti‐inflammatory drug use and triple therapy. In addition, dose‐dependent trends against gastric cancer risk were also shown with individual antipsychotic compounds including thioridazine, haloperidol, sulpiride, clozapine, olanzapine, quetiapine, amisulpride, and risperidone. A sensitivity analysis showed that second‐generation antipsychotics had significant dose‐dependent effects in reducing the risk of gastric cancer risk in patients with and without peptic ulcer disease. CONCLUSIONS: Antipsychotic use was inversely associated with gastric cancer risk, and dose‐dependent effects against gastric cancer were also seen with several individual antipsychotic compounds.