Low-dose acetylsalicylic acid for cancer prevention considering risk factors: a retrospective cohort study

PURPOSE: Aspirin (acetylsalicylic acid) has been reported to protect against certain cancers. However, patient-related risk factors may moderate protective effects, including excess weight, smoking, risky alcohol use, and diabetes. We explore the cancer-risk relationship between aspirin intake and those four factors. METHODS: Retrospective cohort study of cancers, aspirin intake, and four risk factors in persons aged ≥50 years. Participants received medication during 2007-2016, and cancers were diagnosed in 2012-2016. Adjusted hazard ratios (aHR) for 95% confidence intervals (95%CI) were calculated for aspirin intake and risk factors using Cox proportional hazard modeling. RESULTS: Of 118,548 participants, 15,793 consumed aspirin, and 4003 had cancer. Results indicated a significant protective effect of aspirin against colorectal (aHR: 0.7; 95%CI: 0.6-0.8), pancreatic (aHR: 0.5; 95%CI: 0.2-0.9), prostate (aHR: 0.6; 95%CI: 0.5-0.7) cancers and lymphomas (aHR: 0.5; 95%CI: 0.2-0.9), and also, although not significantly, against esophageal (aHR: 0.5; 95%CI: 0.2-1.8), stomach (aHR: 0.7; 95%CI: 0.4-1.3), liver (aHR: 0.7; 95%CI: 0.3-1.5), breast (aHR: 0.8; 95%CI: 0.6-1.0), and lung and bronchial (aHR: 0.9; 95%CI: 0.7-1.2) cancers. Aspirin intake was not significantly protective against leukemia (aHR: 1.0; 95%CI: 0.7-1.4) or bladder cancer (aHR: 1.0; 95%CI: 0.8-1.3). CONCLUSIONS: Our results suggest that aspirin intake is associated with a reduced incidence of colorectal, pancreatic, and prostate cancers and lymphomas.