Additional Study Information: The purpose of this study is to find out if ODM-201 is effective at keeping hormone-sensitive prostatecancer under control when given in addition to standard treatment which includes androgen deprivation therapy (ADT) and docetaxel chemotherapy for six cycles. A total of approximately 1,300 men will take part in this study at a number of different locations internationally. Subjects will have a 1:1 chance of receiving ODM-201 and a 1:1 chance of receiving placebo. Placebo looks identical to the active drug but does not contain any active drug (a fake treatment). In either case, subjects will receive standard treatment with ADT and docetaxel chemotherapy for six cycles. Subjects will have started ADT before taking part in this study.