Digoxin and prostate cancer survival in the Finnish Randomized Study of Screening for Prostate Cancer

BACKGROUND: Protective effects have been suggested for digoxin against prostate cancer risk. However, few studies have evaluated the possible effects on prostate cancer-specific survival. We studied the association between use of digoxin or beta-blocker sotalol and prostate cancer-specific survival as compared with users of other antiarrhythmic drugs in a retrospective cohort study. METHODS: Our study population consisted of 6537 prostate cancer cases from the Finnish Randomized Study of Screening for Prostate Cancer diagnosed during 1996–2009 (485 digoxin users). The median exposure for digoxin was 480 DDDs (interquartile range 100–1400 DDDs). During a median follow-up of 7.5 years after diagnosis, 617 men (48 digoxin users) died of prostate cancer. We collected information on antiarrhythmic drug purchases from the national prescription database. Both prediagnostic and postdiagnostic drug usages were analysed using the Cox regression method. RESULTS: No association was found for prostate cancer death with digoxin usage before (HR 1.00, 95% CI 0.56–1.80) or after (HR 0.81, 95% CI 0.43–1.51) prostate cancer diagnosis. The results were also comparable for sotalol and antiarrhythmic drugs in general. Among men not receiving hormonal therapy, prediagnostic digoxin usage was associated with prolonged prostate cancer survival (HR 0.20, 95% CI 0.05–0.86). CONCLUSIONS: No general protective effects against prostate cancer were observed for digoxin or sotalol usage.