Effect of frequently prescribed drugs on gastric cancer risk

Gastric cancer is the fifth leading cancer worldwide. Infection with Helicobacter pylori represents the major risk factor, but only a small fraction of infected individuals will develop neoplasia. The progression of advanced gastric lesions to cancer is influenced by characteristics of the bacterial strain, host genetic and environmental factors. Recently, the effect of medications on gastric cancer risk has gained interest, because many commonly prescribed drugs affect gastric homeostasis. While non-steroidal anti-inflammatory drugs (NSAIDs) are a frequent cause of gastric ulcer disease, low-dose aspirin has been propagated for chemoprevention of various tumour entities. Beneficial effects of cyclooxygenase-inhibition for gastric cancer prevention is plausible, but its clinical relevance remains unclear. Furthermore, anti-tumorous effects have been postulated for statins and metformin. On the contrary, proton pump inhibitors (PPIs), which are commonly used for prevention of gastric ulcers and bleeding, have been associated with an increased gastric cancer risk in large observational studies. Most of these observations still require confirmation in prospective controlled trials. NSAIDs, statins and metformin have also been investigated as concomitant cancer treatment, but studies did not show convincing results to date. Here, we review the available evidence and possible mechanisms for the role of PPIs, NSAIDs, statins and metformin in gastric carcinogenesis, and discuss possible implications for clinical practice.