Hi Sidekick-
Definitely get a second read from Epstein on your biopsy slides - you don't want to get a treatment for a disease you don't have.
Don't get lost in the weeds - ductal and neuroendocrine are VERY rare variants (there are dozens more). If you had any of them, your pathology report would have noted them already.
Some kinds of prostate cancer just do not put out a lot of PSA. That typically happens with higher grade PC like Gleason 9. This is common.
Your TURP can cause problems with radiation. You do have higher risk of incontinence after radiation because of it. Although I believe radiation is the way to go with a Gleason 9, I think you should talk to surgeons as well. Ash Tewari would be a good choice.
I don't know who you talked to about
CyberKnife, but the specialist with the most experience is Dr Alan Katz in Flushing. If you can get past his lack of gravitas and the ambience of his office, the guy really knows his stuff. In fact, he just presented his 8-year study of SBRT for the treatment of high risk men, the longest running and largest (link below). I know he has treated guys with prior TURP, and he does not use ADT or external beam with it:
Management of high-risk prostate cancer with 5-treatment stereotactic body radiotherapy: Long-term results.The radiation standard of care for high risk is external beam with a brachytherapy boost, and it gets great oncological results. But it does incur more urological side effects, and your prior TURP is definitely aa risk factor for that. The undisputed master of this in NYC is Michael Zelefsky at MSK. He has done more than anyone, and if you are a candidate for it or not, you should feel comfortable taking his word for it.