Abiraterone Acetate Plus Prednisone Induced Bilateral Avascular Necrosis of the Femoral Head

Abiraterone acetate (AA) is an inhibitor of cytochrome P450c17 that suppresses androgen synthesis from steroid precursors.Prednisone (P) is coadministered with AA to correct the glucocorticoid deficiency resulting from AA-induced alterations in steroid synthesis and to suppress excessive mineralocorticoid effects.We report bilateral avascular necrosis of the femoral head in a patient treated with AA+P; this condition is usually seen with long-term, high-dose glucocorticoid use.A 54-year-old male patient was diagnosed with castration-resistant metastatic prostatic adenocarcinoma (Gleason score 4+5).Following progression on androgen deprivation therapy+docetaxel, AA+P treatment was initiated.During this treatment period, the patient was in remission for thirty months; later, he developed bilateral avascular necrosis of the femoral heads and was referred to orthopaedics.Core decompression surgery was performed on both femoral necks due to avascular necrosis.Management and outcome: AA+P treatment was not discontinued because of the highly successful results in treating prostate cancer, and the patient remains in remission while continuing this treatment.AA+P is a treatment for prostate cancer that inhibits androgen synthesis.Although P is administered in low doses to prevent abiraterone-induced reductions in glucocorticoid levels, serious glucocorticoid side effects may, in rare cases, develop in these patients.To our knowledge, this is the first report of such a side effect in the literature.