Objectives: To analyze the influence of aspirin (ASA) intake on PSA values and prostate cancer (PCa) development in a prospective screening study cohort.
Methods: 4314 men from the Swiss section of the European Randomized Study of Screening for Prostate Cancer (ERSPC) were included. A transrectal prostate biopsy was performed in men with a PSA level ≥ 3 ng/ml. Mortality data were obtained through registry linkages. PCa incidence and grade, total PSA, free-to-total PSA and overall survival were compared between ASA users and non-users.
Results: Median follow-up time was 9.6 years. In 789 men (18.3%) using aspirin [ASA +], the overall PCa incidence was significantly lower (6.8% vs. 9.6%, p = 0.015), but the multivariate Cox regression analysis showed no significant decrease in risk of PCa diagnosis (HR 0.84, p = 0.297). Total PSA values were significantly lower in ASA users for both baseline (1.6 vs. 1.8 ng/ml, p = 0.007) and follow-up visits (1.75 vs. 2.1 ng/ml, p < 0.001). Multivariate Cox regression analysis predicted significantly higher overall mortality risk among ASA users (HR 1.46, p = 0.009).
Conclusions: In our study population, PCa incidence was significantly reduced among patients on aspirin. While we did not observe a statistically significant PCa risk reduction during the follow-up period, we found lower PSA values among ASA users compared to non-users, with a more distinct difference after 4 years of ASA intake, suggesting a cumulative effect and a potential protective association between regular ASA intake and PCa development. As for clinical practice, lowering PSA cutoff values by 0.4 ng/ml could be considered in long-term ASA users to avoid a potential bias towards delayed PCa detection.
Keywords: Acetylsalicylic acid; Aspirin; Chemoprevention; Prostate cancer; Prostate-specific antigen; Screening.