@jl99 Anything below 0.1 is generally considered clinically insignificant, meaning that the only action would be to continue monitoring. The main value of ultra sensitive PSA tests seems to be to detect upward trends below 0.1 that potentially give advance warning of a biochemical recurrence.

This year I’ve had three ultra sensitive PSA tests (Labcorp) following salvage radiation in late 2025. Sequentially, the values are 0.086, 0.113 and 0.100. The average of these values is 0.100. Ironically, going into salvage radiation, my PSA was 0.094. My urologist said it best, “The data so far indicate that your PSA is very low and stable, but we will continue with frequent monitoring.”

From numerous discussions and readings, I’ve learned that there is a lot of potential noise in those second and third decimal places. Ultra sensitive values can bounce around for reasons having nothing to do with prostate cancer. Only when there is a persistent upward trend should there be cause for concern. The trick is to convince one's anxious brain of that.

I should mention that even though my usPSA was 0.094 just prior to salvage radiation, two prior normal PSA tests yielded 0.11 and 0.12 AND I had a palpable nodule in my prostate bed that lit up like crazy on a PSMA PET scan (unusual for low PSA, but there you have it). My PSA had been undetectable for ten years following my prostatectomy in 2015. The “glowing", palpable nodule was the primary evidence for a local recurrence, more than my PSA. The 0.11 PSA was primary data for ordering a PSMA PET scan.