Finally I should note there is such a thing (as mentioned by one user here) as "persistent PSA" after RP. I don't think it's that common but you could have a PSA in the 0.03 to ~0.15 range that remains in that range indefinitely, also termed by another user here as "stable PSA". This throws a monkey wrench into making early salvage treatment decisions. I had bilateral nerve sparing and am at 7 months post RP and my erections are slowly coming back (were a 10/10 pre-RP and at 7 months I'm at about a 5-6/10 erection and Urologist says I will eventually recover to a 9/10 (I'm only 54 years old.) BUT, if I do salvage radiation, that will be the nail in the coffin as far as achieving erections due to the blood vessel damage from the radiation, so no erections without a pump, injections or high-dose Viagra/Cialis (which may not be enough.) I think personally I would error on the side of caution and assume BCR at 0.03 and go for early salvage therapy for a higher chance of cure at the expense of significant permanent loss of EF. Versus waiting several months to see if my PSA will stabilize while the micro-metastatic cancer cells could be spreading farther out beyond the field of radiation during that time. Your EF is a moot point when you're on ADT, Chemo or are dead.