Hi Tony,
I'd suggest it is the scan results that you need to focus on. The biopsy can give only part of the situation as Ray mentions correctly.
We don't even know how much of the core was found with P.Ca. Was it 99% cancer or only 5% ? Even then, the needle may have just clipped the edge of tumour giving a false impression of area affected.
Likewise, the psa may be less helpful. With high grade Gleasons, sometimes the psa output is very low. In other cases it can be in the thousands with a similarity of spread. Different variants no doubt. I have known men who are no longer with us whose psa didn't rise above say 10'ish.
I'm doubtful that any local treatment to the prostate would be offered with visible & active bone mets. Surgery certainly not & radiation probably kept on the shelf for dealing with any pelvic pain if it should ever occur. ( There is a fixed limit on pelvic radiation amounts. )
So, any extra treatments would be systemic ones most likely. e.g. Chemo, or trying one of the more powerful newer drugs like Abiraterone or Enzalutamide earlier rather than later.
I think that the medics will want to give the current HT time to judge response. Only an adventurous Onco or a trial will bring in chemo early usually. If any pain started then a more powerful systemic treatment as mentioned might be brought forward.
Early chemo is still under review & trial. Probably worth bringing up at each meeting & discussing the Oncologist's approach at your hospital. It can vary a bit. Only your medical team have the full details & it seems sensible to ask the questions and then see how satisfied you are with their answers. e.g. Are they aiming to try & eradicate as much of the P.Ca. as possible or are they putting quality of life above all else ?
Personally, I believe in hitting hard. And accept the side effects as part of the treatments. Others favour the least intervention for as long as possible.