Effect of Aspirin on Melanoma Incidence in Older Persons: Extended Follow-up of a Large Randomized Double-blind Placebo-controlled Trial

The effects of aspirin on melanoma are unclear, with studies reporting conflicting results. Data from two periods of the ASPirin in Reducing Events in the Elderly (ASPREE) study; the randomized placebo-controlled trial period examining daily 100 mg aspirin in older adults with a median follow-up of 4.7 years, and the second period, an additional 2 years of observational follow-up, were utilized in this secondary analysis to examine whether aspirin exposure is associated with a reduced cutaneous melanoma incidence. All melanoma cases were adjudicated and Cox proportional hazards models were used to compare incidence between randomized treatment groups. ASPREE recruited 19,114 participants with a median age of 74 years. During the trial period, 170 individuals (76 aspirin, 94 placebo) developed an invasive melanoma, and no significant effect of aspirin was observed on incident melanoma [HR = 0.81; 95% confidence interval (CI), 0.60–1.10]. Including the additional 2 years of observational follow-up (median follow-up of 6.3 years), 268 individuals (119 aspirin, 149 placebo) developed an invasive melanoma, and similar results were observed (HR = 0.81; 95% CI, 0.63–1.03). A reduced number of events was observed with aspirin among females in a subgroup analysis (HR = 0.65; 95% CI, 0.44–0.92); however, the interaction effect with males (HR = 0.92; 95% CI, 0.68–1.25) was nonsignificant (P = 0.17). Our findings from this randomized trial do not provide strong support that aspirin is associated with a reduced risk of invasive melanoma in older individuals. Additional studies are required to further explore this relationship.