G7 PC need advice

Sorry to hear that your PSA Nadir didn't drop below 1.6. That's usually not a good sign of successful primary radiation treatment. I'm not familiar with the term "Gleason Peak". If your Gleason score was 8, then I'm surprised that you weren't given ADT before and during your proton treatment.

Usually the the standard definition of BCF is reached and then a PSMA is scheduled to see what that says and go from there. In your case that would be PSA of 3.6. You don't say if your RO prescribed ADT or if you're seeing an MO.

As you can see from my signature, I too had Proton therapy and it failed after 9 years. I wish I had not waited for the ASTRO definition of BCF and fought to have a PSMA after 3 consecutive increases. My Nadir was .75 and I had incremental increases over several years to 1.19. I believed I was in early failure but my RO insisted I had to wait until my PSA rose to 2.75. My urologist thought it was normal remaining healthy prostate producing PSA. In retrospect I think I could have found another doctor who might have ordered the PSMA.

This is a case where you need to get the best medical advice. I would be seeking help at a major cancer center. Good luck!