I have very similar time line as your husband I was 15 months post prostatectomy when my psa reached .13 from previous .06 3 months earlier My urologists then had me get a PSMA pet scam, no cancer found/detected which was expected. He than had me had me see urologist Rad Onc who only specializes and prostrate cancer, after consultation I was put on ADT Orgovix which knocked my psa to undetectable within 3 weeks , I expect to be on this for at least 2 more months. I than began my round of 39 treatments which I completed last week (prostrate bed and LN areas) and am now waiting for 6 week for my next psa. I was stage 4a so I took an aggressive approach which both my primary, and urologist felt was the best course of action before my Psa reached .2 I hope this helps on his quest we are all in this together.