I do not know full details of your diagnosis.
Here are my comments in addition to my previous posts under "Really high PSA" and "Hormone therapy"
Gleason 8 and high PSA indicates high risk cancer. Although scans have not clearly determined bone involvement, it is prudent to approach this as being of high risk that mets could well be a distinct prospect, and treat this in a systemic way.
"" However they say that there is most likely microscopic cancer cells floating around his body""
Answer: I agree. Scans might not show clusters at an early stage.
"" Both doctors state that he is not a candidate for surgery""
Answer: It is true that Surgery and Radiation are local treatments that can not "cure" cancer that is no longer local cancer contained in the prostate. Surgery or Radiation can and are used in addition to hormone therapy to "debulk" the main tumor, and men often do better long term this way. This depends on overall health and bearing in mind that each treatment has it's own potential side effects to consider.
"" The first doctor told us that we should start hormone therapy (casodex and a shot that would last 6 months) and then see what kind of treatment could be done afte that""
Answer: there are various kinds of hormone medications available in 3 to 6 month forms. It's best to use casodex (or similar) before starting the main hormone. Casodex is usually used for at leat 14 days and is optional after that. Some men find some kinds of medication more effective or have less problems with one kind compared to another.
It's logical to start hormone therapy now, which enables you to take time to further consider your options and potential side issues involved with additional treatment that might be suggested.
I strongly recommend that you read the book about Hormone Therapy by Dr Charles Myers that I previously suggested. He has a wealth of information, including details on this particular subject. Dr Myers used radiation and hormone therapy for his own high risk cancer about 9 years ago. He has since used hormone therapy for many of his patients since then.
Obtain full print outs of your tests and biopsy report to keep in a folder so you have all your details on hand for future consultations.
Treatment choices often come down to each individual situation, personal preferences, and which side effects are most palatable for you: if you need further help with your decision making, consult a medical oncologist expert in PC. A medical oncologist is not the one who will perform your radiation or treatment, but will give you an objective opinion and guide you through the decision making process.