I was started on HT for two years. Six months in I had one session of HDR brachy with a general anaesthetic, then 15 fraction of EBRT starting a week later.
Aged 53, I was diagnosed G4+5, T3 Extra capsular extension, PSA 25.
Surgeons were not interested in treating me, if I had a relapse it would have upset their statistics. I don't think anyone keeps statistics on radiotherapists so they were happy to have a go.
Very few treatments are possible post RT, however as HDR is confined to the prostate and doesn't do much damage outside the prostate and the EBRT is only given at half strength, it maybe possible to have more RT (I have no evidence for this).
Old Barry had HIFU many years after RT. This would only be possible if the new tumour was in exactly the right position.
Five years on my PSA is <0.1, but as discussed on another thread, you need to look at statistics not just one person's good or bad luck.