Use of low-dose aspirin after a diagnosis of prostate cancer (PCa) is not associated with overall reduced PCa mortality risk, but long-term use might lower the risk, investigators reported.
In a nationwide cohort study of 29,136 patients diagnosed with PCa in Denmark, Charlotte Skriver, MSc, of the Danish Cancer Society Research Center in Copenhagen, and colleagues found no effect of low-dose aspirin use assessed within 1 year after diagnosis on PCa mortality in adjusted analyses, according to study findings published in the Annals of Internal Medicine. Low-dose aspirin use was associated with a significant 12% increased risk of other-cause mortality.
After exposure periods of 5 and 7.5 years after diagnosis, however, low-dose aspirin use was associated with 9% and 18% decreased risks of PCa mortality, respectively, during follow-up (which began 5 and 7.5 years after PCa diagnosis, respectively).
During the 7.5 year exposure period, low-dose aspirin use for at least 1096 days (more than 3 years) and cumulative use of at least 1096 tablets (equivalent to more than 3 years of use assuming a dosage of 1 tablet per day) were associated with a significant 21% and 23% decreased risk PCa mortality, respectively, compared with nonuse, Skriver and colleagues reported.
In most analyses, postdiagnosis low-dose aspirin use was associated with slightly increased other-cause mortality, according to the investigators.
Skriver’s team defined postdiagnosis use of low-dose aspirin (75, 100, or 150 mg) as 2 or more prescriptions filled within 1 year after diagnosis. They defined nonuse as fewer than 2 prescriptions filled. In Denmark, the authors noted, aspirin is available over the counter, but most low-dose aspirin is dispensed by prescription.
The study population had a median age of 70 years at diagnosis. Of the 29,136 patients, 7163 (24.6%) used low-dose aspirin and 21,973 (75.4%) were nonusers. Investigators followed up patients from 1 year after PCa diagnosis to the date of death, emigration, or December 31, 2015. During a median follow-up of 4.9 years, 7633 patients died from PCa and 5575 died from other causes through 2015.
Skriver C, Dehlendorff C, Borre M, et al. Use of low-dose aspirin and mortality after prostate cancer diagnosis: A nationwide cohort study. Ann Intern Med. 2019; published online ahead of print. DOI: 10.7326/M17-3085