Failure to achieve castrate level of serum testosterone during luteinizing hormone-releasing hormone agonist therapy in a patient with prostate cancer

We report the failure to achieve castrate level of serum testosterone during luteinizing hormone-releasing hormone agonist therapy in a patient with prostate cancer. A 76-year-old man was admitted to our hospital for evaluation of an elevated serum prostate specific antigen (PSA) level (191.10 ng/ml) in August 2011. He was diagnosed with T3aN0M1b prostate adenocarcinoma. A combined androgen blockade using luteinizing hormone-releasing hormone agonist (the 1-month depot of leuprorelin acetate) and antiandrogen was administered. Due to liver dysfunction, antiandrogens, both bicalutamide and flutamide, were stopped. The 1-month depot was switched to the 3-month depot in May 2013, but the patient complained of induration and abscess at the infection site. Leuprorelin acetate was replaced by goserelin acetate. Because no adverse event appeared after injection of the 1-month depot of goserelin acetate, the 3-month depot was administered in October 2013. The PSA level increased gradually, and the testosterone level was greater than 50 ng/dl, that is, above castrate range. The 3-month depot of both leuprorelin acetate and goserelin acetate was not effective for this patient. For this reason, the 1-month depot of leuprorelin acetate was started resulting in a rapid decrease in PSA and testosterone levels. Thereafter, androgen depriving therapy could be continued. Androgen deprivation therapy is the standard treatment for patients with advanced prostate cancer and luteinizing hormone-releasing hormone aims to suppress serum testosterone to castrate range. We recommend assessing the serum testosterone levels during luteinizing hormone-releasing hormone agonist therapy for monitoring treatment efficacy and verifying progression when the PSA level increases.