Antoinette, it is a stressful time for you both but from what you have told us there likely to be a good chance of successful treatment. With cancerous cells detected outside the prostate it is indeed likely that radiotherapy will be the favoured route, and the most modern machines are very good.
The worry comes with the hormone therapy, which can have longlasting effects. I think the two of you need to talk to the oncologist about your fears, and whether the treatment can be adjusted. While oncologists (who after all know a lot more than people on a forum) do believe that blocking testosterone enhances the success rate with radiotherapy, the evidence for the best way to do it is less clear and there should be scope for doing it in a way that gives the best probability of testosterone recovery. One point is the timing, though three years therapy is pretty standard there seems to be agreement that the treatment in advance of radiotherapy is particularly effective (it can shrink the prostate cells to produce a better radiotherapy target) and the time afterwards might perhaps be reduced. There is also a choice of drugs that can be used for the hormone therapy, and some seem to give a better chance of recovery than others even though they might carry separate side effects; those are all things worth discussing.
Good luck for next week.