Use of Low-Dose Aspirin and Mortality After Prostate Cancer Diagnosis: A Nationwide Cohort Study.

Abstract

Recent studies suggest that aspirin use may improve survival in patients with prostate cancer. To assess the association between postdiagnosis use of low-dose aspirin and prostate cancer mortality. Nationwide cohort study. Denmark. Men with incident prostate adenocarcinoma between 2000 and 2011. Nationwide registry data on tumor characteristics, drug use, primary prostate cancer therapy, comorbidity, and socioeconomic parameters. Postdiagnosis use of low-dose aspirin (75 to 150 mg) was defined as 2 or more prescriptions filled within 1 year after prostate cancer diagnosis. Follow-up started 1 year after prostate cancer diagnosis. In secondary analyses, low-dose aspirin use was assessed within exposure periods of 5 or 7.5 years after prostate cancer diagnosis. Of 29136 patients (median age, 70 years), 7633 died of prostate cancer and 5575 died of other causes during a median follow-up of 4.9 years (interquartile range, 3.1 to 7.2 years), through 2015. Postdiagnosis low-dose aspirin use was associated with adjusted hazard ratios (HRs) of 0.95 (95% CI, 0.89 to 1.01) for prostate cancer-specific mortality and 1.12 (CI, 1.05 to 1.20) for other-cause mortality. The secondary analyses showed that prostate cancer mortality was slightly reduced with low-dose aspirin use after the 5-year (HR, 0.91 [CI, 0.83 to 1.01]) and 7.5-year (HR, 0.84 [CI, 0.72 to 0.97]) postdiagnosis exposure periods, notably among patients filling prescriptions for a large quantity of low-dose aspirin tablets during the 7.5-year period. Data on over-the-counter aspirin use were unavailable. Some residual confounding was possible as a result of incomplete data on some prognostic factors. The study did not support an overall effect of postdiagnosis low-dose aspirin use on prostate cancer mortality. However, results for extended exposure periods suggest that low-dose aspirin use might be inversely associated with prostate cancer mortality after 5 years from cancer diagnosis. Danish Cancer Society.