Introduction
Androgen deprivation therapy (ADT) is a standard of care for metastatic prostate cancer (PCa), however, eventually, all men relapse. Docetaxel has long been the only agent demonstrated to improve overall survival in castration-resistant prostate cancer (CRPC) patients(9). New androgen receptor-axis-targeted agents (ARAT) have improved the prognosis of men with CRPC patients. Although ARAT improves survival in CRPC PCa patients(6), they remain incurable and eventually progress. A new approach to hormonal therapy is necessary. It has been reported that the growth of some PCa cells can be inhibited by supraphysiologic levels of androgens(2). High doses of testosterone (T) are administered monthly and the supraphysiologic T level is followed by a rapid drop to castration levels during each cycle of therapy(2). This was called ”bipolar androgen therapy” (BAT). Although the mechanisms of BAT are currently poorly understood, clinical responses have now been observed in men with PCa treated with high doses of T. Although several clinical trials using BAT have been reported (3, 4), its application for CRPC is still controversial. We report on 4 heavily pretreated CRPC patients successfully treated with supra-physiological doses of T.