Experience with androgen deprivation therapy for prostate cancer in Japan and future perspectives

Novel anti-androgens and androgen biosynthesis inhibitors have been developed to treat castration-resistant prostate cancer. However, knowledge of androgen deprivation therapy (ADT) has not been developed in the criticism, including information regarding the adverse effects of hormonal therapy. We hypothesize that there are ethnic differences in the efficacy and adverse effects of ADT; therefore, this review summarizes the experience of ADT, mainly in Japan. A risk stratification instrument, the Japan Cancer of the Prostate Risk Assessment (J-CAPRA) score, was developed based on the Japan Study Group of Prostate Cancer registry, which is a large, multicenter, population-based database. It revealed that clinical outcomes were substantially better for males treated with ADT in Japan compared with those in the United States. Moreover, there were small survival differences in patients with localized and locally advanced cancer who received local therapy and primary ADT in another Japanese cohort study. In terms of adverse effects, including bone loss and cardiovascular risk, ADT appears to be better tolerated in Japanese populations than in Western cohorts. An ongoing randomized controlled trial of a trimodality treatment comprising brachytherapy, external beam radiation therapy, and neoadjuvant with or without adjuvant ADT in patients with localized high-risk prostate cancer will provide novel insights regarding adjuvant ADT. As a future perspective, the optimal selection of the type of primary ADT, including combining androgen blockade and novel hormonal compounds, adjusted according to each patient's clinicopathological background, may provide better clinical outcomes in patients with advanced prostate cancer.