Spironolactone use and risk of incident cancers: a retrospective, matched cohort study

Aims Spironolactone is widely used to treat heart failure, hypertension and liver disease with increased usage in recent years. Spironolactone has endocrine effects that could influence cancer risks and historical reports suggest possible links with increased risk of certain types of cancer. The aim of this study was to assess the effect of spironolactone exposure on cancer incidence. Methods A pharmacoepidemiological propensity score-matched cohort study was performed to assess the effect of spironolactone exposure on cancer incidence. Cox proportional hazards models were used to analyse time to first diagnosis of each prespecified cancer and hazard ratios for spironolactone exposure are presented. The setting for the study was UK primary care using the Clinical Practice Research Datalink. The participants were 74 272 patients exposed to spironolactone between 1986 and 2013, matched 1:2 with unexposed controls. The prespecified primary outcomes were the first incidence of ovarian, endometrial, pancreatic, colorectal, prostate, renal cell, pharyngeal and thyroid cancers, and myelomonoblastic/-cytic leukaemias. Secondary outcomes were the remaining 27 types of cancer. Results There was no evidence of an increased risk of any cancer associated with spironolactone use. Spironolactone use was associated with a significantly lower risk of prostate cancer (hazard ratio 0.69; 95% confidence interval 0.60–0.80, P < 0.001). Conclusions In this study, spironolactone use was associated with a lower incidence of prostate cancer, the most common cancer in men in the UK. The possible mechanisms and clinical implications merit further investigation.