Getting his PSA down to 5 from over 600 is a good response. On the trials that used these treatments, median survival was 5 years. That is, 50% of patients lived more than 5 years. Treatments that are being trialled now should improve significantly on this. Typically a patient can benefit from hormone therapy for 1 to 2 years, sometimes more, then there are further treatments available such as enzalutamide and abiraterone. As far as the leg pain is concerned I think you need to ask your doctor or nurses, or cancer support people, what can be done about this, as it is hard for someone like me to advise. Good luck!