I'm 10 years younger than you and was diagnosed with Gleason 9 (5+4) that had already metastasized. I've been on ADT/ARSI for 14 months and had IMRT to prostate and SBRT to bone mets. Side effects are apparent but not debilitating. If, knowing what I know now, I was diagnosed @ 81, I would have no problem following the same treatment plan. That said, one of the unfortunate things in combatting this disease, is that no two people react the same to treatment protocols so my experience may not be yours. Also, only you can define what acceptable quality of life is for you. Be thorough in your research and in questioning your care team. Best wishes in your treatment decision and outcome.