Aspirin use reduces cancer risk in betel nut chewers: a nationwide population-based cohort study.

Betel nut chewing, common in several Asian populations, is linked to increased cancer risk, including oral, esophageal, gastric, and hepatocellular carcinoma. Aspirin shows potential as a chemopreventive agent. This study investigates the association between aspirin use and cancer risk among betel nut chewers. Betel nut chewers aged 18 and older were included, with aspirin use defined as at least 28 cumulative defined daily doses (cDDDs). Propensity score matching and Cox proportional hazards models, adjusted for time-varying covariates, were used to assess cancer risk. The study included 46,302 betel nut chewers, equally divided between aspirin users and non-users. Aspirin use was associated with a 31% reduction in overall cancer risk (adjusted hazard ratio [aHR], 0.69; 95% confidence interval [CI], 0.66 to 0.73; P<0.0001). A dose-response relationship was observed, with higher cDDDs of aspirin corresponding to greater reductions in cancer risk. The highest quartile of aspirin use (Quartile 4) showed a 62% reduction in cancer risk (aHR, 0.38; 95% CI, 0.34 to 0.41; P<0.0001). Daily aspirin intensity was also associated with a significant reduction in cancer risk, with doses greater than 1 DDD showing an aHR of 0.54 (95% CI, 0.47 to 0.61; P<0.0001) compared to 1 DDD or less. Aspirin use significantly reduces cancer risk among betel nut chewers in a dose-dependent manner. These findings suggest aspirin as a potential chemopreventive agent in high-risk populations, warranting further investigation.