The association between proton pump inhibitors (PPI) use for gastro-esophageal reflux disease (GERD) and lung cancer (LC): A nested case-control study.

1562 Background: Data suggests that GERD with recurrent reflux and microaspiration of stomach contents, may be associated with lung injury, inflammation, activation of proliferative signals, and eventually DNA damage and malignant transformation. Recently, a large population based cohort study found that GERD may increase the risk of lung cancer in Asians. In the present nested case control study, we aimed to evaluate the association between PPI use as a surrogate for GERD and lung cancer in a large western population. Methods: We conducted a matched case-control study within a population-representative database from the United Kingdom. Study cases were defined as individuals with any diagnostic code of lung cancer. For every case, four eligible controls were matched on age, gender, practice site, time and duration of follow-up. Exposure of interest was PPI use prior to cancer diagnosis. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for lung cancer were estimated using conditional logistic regression. Adjustment was performed for smoking. Results: The study population included 19143 lung cancer cases and 74473 matched controls. PPI use was associated with a significantly increased lung cancer risk (adjusted OR 1.70, 95%CI 1.64-1.77, p < 0.001). In a sensitivity analyses we observed similar associations when PPI use was initiated more than one year prior to cancer diagnosis (adjusted OR 1.18, 95%CI 1.13-1.23, p < 0.001) and more than two years prior to cancer diagnosis (adjusted OR 1.15, 95%CI 1.10-1.20, p < 0.001) Conclusions: ChronicPPI use, as a surrogate for symptomatic GERD, may be associated with a higher lung cancer risk.