Consequences of Different Corticosteroids on Serum Potassium and Prostate-Specific Antigen in Patients Receiving Abiraterone for Castration-Resistant Prostate Cancer: A Retrospective Observational Study

Background Abiraterone acetate is an androgen synthesis inhibitor approved for the treatment of castration-resistant prostate cancer (CRPC). Although co-administration of either prednisone or prednisolone at 10 mg/d has been recommended to reduce the risk of abiraterone-induced hyperaldosteronism (notably hypokalemia) and to give adjunctive pain relief effects, whether these glucocorticoids can be substituted by dexamethasone remains unknown. Methods We performed a retrospective review of medical records of patients who were given abiraterone for the treatment of CRPC with either prednisolone (ABI/PSL) 10 mg/d or dexamethasone (ABI/DEX) 0.5 or 1 mg/d between 2014 and 2017 in Juntendo University Nerima Hospital. Demographic and biochemical data including prostate-specific antigen (PSA) level were retrieved from the electronic medical records. Results Fifty-three eligible patients (27 in ABI/PSL group and 26 in ABI/DEX group) were extracted from the records. Both groups showed no significant changes in serum potassium level before and after starting treatment. In the ABI/PSL group, 12 patients (46%) showed elevations of PSA and 7 patients (27%) discontinued treatment within 3 months. In contrast, in the ABI/DEX group, only 6 patients (25%) showed elevations of PSA and 3 patients (13%, all were given dexamethasone 1 mg/d) discontinued treatment. Conclusions Dexamethasone and prednisolone may be equally effective in preventing abiraterone-induced hypokalemia.