Digoxin or other antiarrhythmic drugs are not associated with a clear decrease in the risk of prostate cancer (PCa), but long-term use of digoxin may decrease the risk of high-grade PCa, researchers reported.

Kalle Kaapu, MD, of the University of Tampere in Tampere, Finland, and colleagues studied 78,615 men who participated in the Finnish Prostate Cancer Screening Trial from 1996–2012. In that trial, men were randomized to be screened for PCa with PSA tests at 4-year intervals (screening arm) or to be followed through the national Finnish Cancer Registry (control arm). The researchers used a national prescription database to extract information about antiarrhythmic drug purchases.

During a median follow-up period of 12 years, PCa was diagnosed in 6,639 men, Dr. Kaapu’s group reported online ahead of print in Cancer Causes & Control. The investigators found no significant association between antiarrhythmic drug use and overall PCa risk. Users of either digoxin or sotalol had no decreased risk of PCa compared with those who never used the medications. The researchers obtained similar results when looking at high-grade PCa (Gleason score 7–10) and metastatic PCa. PCa risk tended to decrease with increasing duration of digoxin use, however. Among individuals in the screening arm of the trial, men who used digoxin for 5 years or more had a significant 69% decreased risk of Gleason 7–10 cancer compared with men who never used the drugs.

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Dr. Kaapu and colleagues noted that their results lend some support for oncologic benefits of long-term digoxin use. Previous studies have suggested that digoxin may have a protective effect against PCa. For example, a population-based case-control study by Jonathan L. Wright, MD, of the University of Washington in Seattle, and colleagues found that digoxin use was associated with a non-significant 42% decreased odds of PCa compared with never use, after adjusting for age, race, PSA screening, and family history of PCa, according to a report in The Prostate (2014;74:97-102). Among individuals with 3 or more PSA tests over the preceding 5 years, digoxin use was associated with a significant 56% decreased odds of PCa.