A few clarifications about
what your doctor told you:
1. He is absolutely right that SBRT of cancerous mets will drive your PSA down. That is because the main source of PSA is usually from the larger mets that are detectable. They are the ones that have created a network of blood vessels within the tumors that carry PSA out into the serum. But reducing the PSA is not the same thing as delaying the cancer spread, as far as we currently know. SBRT will afford
local control only; i.e., it will shrink the targeted met and stop it's PSA output. But does that really accomplish any survival benefit? No one really knows for sure, but a recent trial had very equivocal outcomes:
/pcnrv.blogspot.com/2017/12/metastasis-directed-therapy-for.html2. The test at Johns Hopkins was
not of TRT for mHSPC, it was of
bipolar androgen therapy. The difference is important. They alternated periods of complete androgen deprivation to reduce the cancer load, with periods of androgen saturation to keep the cancer cells hormone sensitive (the purpose was of androgen saturation was not to kill the cancer, just to keep it susceptible to ADT). They reported 18-month outcomes in 39 patients:
/pcnrv.blogspot.com/2016/09/testosterone-to-treat-prostate-cancer_5.html