If it was prostate cancer, you would be put on hormone therapy. As far as I can see, you've never been on hormone therapy, so it should be effective very quickly.
Given they haven't done this, I guess they don't think it's prostate cancer, but some other cancer.
Obviously, I don't have all your medical details, but given what you've said, I would push to get it identified via biopsy - you have nothing to lose. Once that's done, there's a chance it might open the door for some systemic treatments.