At 84 are you planning on living forever or a nursing home? If the drugs are keeping your PSA and cancer under control, why add radiation? Don't let the doctors pressure you remember they don't get paid unless they treat you, so they have a built-in bias to treat. Take your time and investigate all options. I am 74 and did the 5-radiation treatment at Mayo. My radiation oncologist wanted to do 28 treatments and 6 months of Lupron for my Gleason 7.