Beneficial prognostic effects of aspirin in patients receiving sorafenib for hepatocellular carcinoma: A tale of multiple confounders

Case–control observational studies suggested that aspirin might prevent hepatocellular carcinoma (HCC) in high-risk patients, even if randomized clinical trials are lacking. Information regarding aspirin in subjects who already developed HCC, especially in its advanced stage, are scarce. While aspirin might be a low-cost option to improve the prognosis, multiple confounders and safety concerns are to be considered. In our retrospective analyses of a prospective dataset (n = 699), after assessing the factors associated with aspirin prescription, we applied an inverse probability treatment weight analysis to address the prescription bias. Analyses of post-sorafenib survival were also performed to reduce the influence of subsequent medications. Among the study population, 133 (19%) patients were receiving aspirin at the time of sorafenib prescription. Aspirin users had a higher platelet count and a lower prevalence of esophageal varices, macrovascular invasion, and Child–Pugh B status. The benefit of aspirin was confirmed in terms of overall survival (HR 0.702, 95% CI 0.543–0.908), progression-free survival, disease control rate (58.6 vs. 49.5%, p < 0.001), and post-sorafenib survival even after weighting. Minor bleeding events were more frequent in the aspirin group. Aspirin use was associated with better outcomes, even after the correction for confounders. While safety concerns arguably remain a problem, prospective trials for patients at low risk of bleeding are warranted.