@heavyphil If PSA goes very high very fast, and they know there's a "fire" somewhere, they have the option to "turn on the sprinkler system," so to speak. With chemotherapy or radioligands (Pluvicto), as with ADT or ARSIs, you don't need to know where the cancer is recurring to go after it.

External-beam radiation (of any sort) is highly effective — I've had it both to my spinal lesion and to my prostate — but it's also precise, so you need to be able to see what you're aiming at.