Toronto, I believe Dr Eugene Kwon at Mayo Clinic in Rochester, might be worth talking to. He treats oligometastatic Prostate Cancer with Radiation. It is somewhat controversial, as to whether it extends survival. But might be worth a visit if you as you say , are interested in exploring it globally. Not sure, maybe he would do a phone consult? Here’s a video from 2014 where he discusses the topic. Be aware things might have changed over the last 5 years.
https://youtu.be/60p98qlwf70Also , c0nsider talking to these guys...
https://www.prostateoncology.com/ They are Medical Oncologists who only treat prostate cancer. Very well known and well regarded, and many here, including me, have consulted with them, and many if those (not me) have been treated by them. They do phone consults, when I talked to them it was $750 (US), but that was 5 years ago.
Good luck, please keep us posted