To the Editor We have read recently published articles investigating the correlation between the use of aspirin and lower incidence of ovarian1 and hepatocellular cancer (HCC)2 with great interest. Although appealing, these results must be interpreted with caution. Two double-blinded, placebo-controlled randomized clinical trials (RCTs)3,4 investigating the effect of low-dose aspirin on primary prevention of cardiovascular disease were recently published. In A Study of Cardiovascular Events in Diabetes (ASCEND) trial,3 aspirin demonstrated a neutral effect on any cancer incidence (relative risk, 1.01; 95% CI, 0.92-1.11). However, the results of the Aspirin in Reducing Events in the Elderly (ASPREE) trial4 were more worrisome. They reported a higher cumulative incidence of cancer-related death (hazard ratio, 1.31; 95% CI, 1.10-1.56) that was accompanied by a somewhat higher incidence of cancer in the aspirin group. It is important to highlight that the results were consistent regardless of the cancer type, and bleeding was excluded as the possible cause of the higher incidence of cancer-related death.4 In addition to being randomized, both trials3,4 included large numbers of patients and had follow-ups of 7.4 and 4.7 years, respectively. Also, both RCTs3,4 included populations with a higher cancer risk (those with diabetes and older age),5 which could make a potential beneficial effect of aspirin on cancer more visible. In our opinion, these trials provide a higher quality of evidence than the exploratory analyses of nonrandomized prospectively collected data.