3 1/2 years after surgery, my PSA hit .2 and I had to have salvage radiation. There’s a good reason to get it at that level. Don’t wait too long. Here are some information about that.

From Ascopubs about what PSA to do salvage radiation.
≤0.2 ng/mL:
Starting at this level maximizes disease control and long-term survival. Patients treated at PSA < 0.2 ng/mL achieve higher rates of undetectable post-SRT PSA (56-70%) and improved 5-year progression-free survival (62.7-75%).
Delaying SRT beyond PSA ≥0.25 ng/mL increases mortality risk by ~50%.

0.2–0.5 ng/mL:
Still effective, particularly for patients with low-risk features (e.g., Gleason ≤7, slow PSA doubling time). The Journal of Clinical Oncology recommends SRT before PSA exceeds 0.25 ng/mL to preserve curative potential.

0.5–1.0 ng/mL:
Salvage radiation remains beneficial but may require combining with androgen deprivation therapy (ADT) for higher-risk cases.

Yup - mad, disappointed, anxious…it’s a freakin curse, man, but what keeps me grounded is having seen friends and family in the rosy bloom of supposed health struck down in months or less with no recourse, no treatment and no hope.
The fact that I have avenues STILL open to me after two rounds with this mofo, keeps me sane and in the fight!
Phil