Purpose: Increasing evidence suggests that aspirin use may protect against prostate cancer. In a nationwide case–control study, using Danish high-quality registry data, we evaluated the association between the use of low-dose aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) and the risk of prostate cancer.
Methods: We identified 35,600 patients (cases) with histologically verified prostate cancer during 2000–2012. Cases were matched to 177,992 population controls on age and residence by risk-set sampling. Aspirin and nonaspirin NSAID exposure was defined by type, estimated dose, duration, and consistency of use. We used conditional logistic regression to estimate odds ratios (ORs), with 95 % confidence intervals (CIs), for prostate cancer associated with low-dose aspirin (75–150 mg) or nonaspirin NSAID use, adjusted for potential confounders.
Results: Use of low-dose aspirin was associated with an OR for prostate cancer of 0.94 (95 % CI 0.91–0.97). Slightly lower ORs were seen with increasing cumulative amount, duration, and consistency of low-dose aspirin use (continuous use, ≥5 years: OR 0.89; 95 % CI 0.82–0.97; ≥10 years: OR 0.86; 95 % CI 0.70–1.06). Nonaspirin NSAID use was associated with a slightly increased OR for prostate cancer (1.13; 95 % CI 1.10–1.15); however, this association was confined to localized disease and did not vary materially with amount, duration, or consistency of nonaspirin NSAID use.
Conclusions: Our study indicates that long-term, consistent low-dose aspirin use may provide modest protection against prostate cancer. The slightly increased risk of only localized prostate cancer with nonaspirin NSAID use suggests a noncausal explanation of the observed association.