Spironolactone, a possible selective androgen receptor modulator, should be used with caution in patients with metastatic carcinoma of the prostate.

The authors report the case of an 80-year-old man who had heavily pretreated castration refractory carcinoma of the prostate and heart failure. Following the introduction of spironolactone to manage his heart failure, the patient experienced clinical and biochemical progression of his prostate cancer. Within 2 weeks of withdrawing spironolactone the patient's prostate-specific antigen returned its previous level. This is the first reported case of clinical and biochemical progression of prostate cancer following the introduction of spironolactone. The authors propose that spironolactone is a selective androgen receptor modulator. Spironolactone should be used in caution with men with prostate cancer, and should not be used to treat oedema, hypokalaemia and hypertension associated with the newly licensed hormonal therapy abiraterone acetate.