@peterj116 Yes, good discussion there—thanks for that link. Just days before I started my salvage radiation last fall, I had the opportunity to have back-to-back blood draws for Quest’s standard PSA test, and Labcorp’s ultra sensitive test.

Quest came back at 0.11—the same as three months earlier when I went started down the path of diagnosis for recurrent PSA.

Labcorp came back at 0.094. Basically, I read these both as 0.1. No significant difference. However, it interesting to note that if I had done the uPSA test back in June 2025, and got a < 0.1 value (instead of 0.11 from Quest), no alarms would have gone off and my docs would have told me to come back in a year. That could have been a fateful decision because both PSMA PET and MRI scans confirmed that a small, palpable nodule in my prostatic fossa was favored to be cancerous.

Three months after RT, my first uPSA Labcorp test yielded 0.086. Another data point is needed to see if that is the start of a downward trend, which hopefully it is. But like I said, if I just stay at 0.08-0.09 for the rest of my days, I’d be happy with that (no further treatment needed).

I pressed both my RO and urologist on small changes in uPSA values and if doubling time really means anything if someone goes from 0.02 to 0.04. Neither thought it did, but acknowledged that there was a lack of consensus among medical professionals. I 100% agree though that trends are significant, just like with regular PSA tests.