Hi Farz. It will help if you can create a signature with your father's information in it. That way people can give some better informed advice.
I have added you (for your father) to the G9 Crew thread, in the exclusive G10 group. We see very few with that diagnosis, so we recognize he has a serious fight ahead of him. Here is a link to that thread (it's the one you've posted briefly on already):
The Gleason 9 Crew -- Part 2, continued.There are other G10s there, and you may learn by reading their threads. They are linked right next to their names on that post.
Also, at the top of the forum's front page is a "sticky" note that has information for the newly diagnosed. Your father is no longer new to this, but there may be useful information there. This is a complex disease, with many treatments, most only useful at specific stages of the disease. Right now, your initial question is so broad that it is hard to be helpful.
If you provide some more information about
his situation and treatments he has already had, and ask a more specific question, I'm sure some of the smart people here can help.