My husband had a Gleason 4+5 biopsy as well. We learned from the Radio Oncologist that the radiation kills the cancer cells effectively but not immediately. They die in slow motion and it takes roughly one year until the dying process and the radiation's effect stop. For a "standard" PCa cell this is fast enough since PC grows slowly. However, very aggressive cancer cells are highly active and more robust. They could be still able to proliferate so that the cancer is not suffocated enough or may even sneak out of the radiation area. Hence, ADT kind of paralyzes or freezes the cells in order to suppress their activity during the radiation's effective time. This is the reason why radiation alone is not suited aggainst aggressive cancer as in your case. We had not understood why they recommend ADT for so much longer than this one year post radiation, apart from a more is more strategy (which is not always a good one). However, since my husband decided for surgery, we did not follow up on this topic any more.

Ask your RO about this and whether one year wouldn't be a good compromise in your case, or maybe even a bit shorter. It seems that the effect of ADT doesn’t end abruptely when you stop it. All the best to you!