Hi Steve,
my prostatectomy was a failure from the get go too and I have had salvage RT but it will be a while before they test to see if it has worked so I am in that awful state of Limbo that we all experience awaiting results.
I would ask your doc for a PSMA PET scan to see if they can find the source for the PSA which is likely to be a tumour somewhere and targeted Lutetium 177 treatment sounds v promising to me.
In the UK they can then use targeted treatment like SABR radiotherapy to deal with one or maybe two tumours but more than that they may decide on another approach.
I have been looking in to injectable Lutetium 177 treatments that use a radioactive ligand which is attached to a molecule that binds to cells expressing PSA and it is very focused as the the radiation only travels very locally and so kills the tumour without damaging the healthy surrounding cells much.
They make it very difficult to get a PSMA PET scan in England and even more difficult to get L177 treatment which they reserve for late stage metastasis.
However I think in Canada you are much more likely to be able to obtain it as the radioactive materials are actually made there and I have read of people having it at your stage with good results.
Crispin who posts on here has had it and has not needed the full 6 injections 6 weeks apart as PSA dropped nicely after just two rounds which is very encouraging indeed.
Best
Al