Low-dose aspirin and risk of gastric cancer development after Helicobacter pylori eradication: a territory-wide study with propensity score analysis

Abstract

Introduction: Individuals remain at risk of developing gastric cancer (GC) despite eradication of Helicobacter pylori (HP). Although aspirin was shown to be associated with a reduced GC risk in HP-infected subjects, it remains uncertain whether aspirin can reduce GC risk in HP-eradicated subjects. This study aimed to investigate the chemopreventive effect of aspirin in HP-eradicated subjects. Method: Subjects who had received clarithromycin-based triple therapy between 2003 and 2012 in all public hospitals in Hong Kong were identified. Those who failed HP therapy and developed GC within 12 months were excluded. The observation period started from the commencement of HP therapy (index date), and patients were censored at the end of study (December 2015), death, or GC diagnosis. Aspirin use was defined as once or more weekly use. Cox proportional hazard model with propensity score adjustment for covariates (including age, sex, comorbidities, and concurrent medications) was used to derive the hazard ratio (HR) and 95% confidence interval (CI) of GC with aspirin use. Results: Of the 63 605 eligible subjects (with a median follow-up of 7.6 years), 169 (0.27%) developed GC with an incidence rate of 3.5 per 10 000 person-years. Aspirin use was associated with a reduced GC risk (HR=0.30, 95% CI=0.15-0.61). Compared with the reference group (never use), more frequent aspirin use showed a significant decreasing trend of GC risk (Ptrend<0.001), with lowest risk observed among daily users (HR=0.21, 95% CI=0.05-0.94). Compared with never use, a longer duration of aspirin use was also associated with a lower risk of GC (<2 years: HR=0.92, 95% CI=0.51-1.64; 2-5 years: HR=0.27, 95% CI=0.09-0.80; ≥5 years: HR=0.07, 95% CI=0.02-0.31; Ptrend<0.001). Moreover, a lower risk was observed with a higher aspirin dose (<100 mg: HR=0.38, 95% CI=0.18-0.79; ≥100 mg: HR=0.15, 95% CI=0.03-0.65; Ptrend<0.001). Conclusion: Aspirin use was associated with a reduced GC risk in a dose-response manner in HP-eradicated subjects.