The evidence strength of a meta-analysis of aspirin for primary prevention of cancer

Dr. Tarek Haykal et al. (145:1795–1809, 2019) reported a meta-analysis of aspirin for the primary prevention of cancer in individuals without known cancer. The authors found that aspirin use was not associated with significant reduction in cancer mortality or incidence, but with higher rates of bleeding. The findings of this study added some evidence to the clinical practice. However, several issues might have compromised the strength of the evidence of this systematic review. If the investigators could have further clarified the inclusion and exclusion criteria, included all eligible studies, extracted data more meticulously, and performed more necessary sensitivity analyses to confirm the robustness of their findings, the strength of evidence of this meta-analysis would have been stronger.