Mr G, welcome from one whose PCa predates yours by nearly ten years. I too was a Gleason 9 but my PSA was 63. Luckily I had no bone spread, indeed no evident spread at all. Early chemo was not an option in those days, so I've been on the zoladex and Abiraterone route until just recently, when the dreaded spread became apparent. I'm about a week behind you on the docetaxel with my fourth cycle starting next Wednesday. I too have seen good PSA drops with each cycle and my side effects have been confined to energy loss, mild headaches and slightly nausea, all quite bearable.
My point in writing is to assure you that you DO have a future and should feel confident about living with the cancer. Neither of us is likely to be cured but we should not die of the thing. That is why it is important in terms of diet and exercise to be heart-fit. We can prolong the pleasure life brings by minimising the risks of other things bumping us off. That will possibly have a spin off effect of helping to fight the cancer, too.
I hope it continues to go well with you.
Best wishes
AC