Not sure this adds anything.

Your question, "does PSA reach 0?"

No...

Depending on which test, which assay and which lab., it may be reported to one, tow or three decimal points.

Generally, for single decimal point it is reported at < .1. Does that mean it's zero? No! It could be .03 but the test, assay, measuring equipment and the medical facility does not detect or report to two or three decimal points?

Why not use the USPSA? The discussion generally centers around the medical usefulness of doing so. Some subscribe that an USPSA may just cause unnecessary anxiety and at levels of for example .02 or .03, no action is required by the patient or his medical team.

Others take a different view and say that USPSA may provide early indication of activity and inform a treatment decision .

I kind of use a hybrid of the two...

In my case, my medical team uses USPSA, two decimal places, but interestingly, our decision criteria says we don't act until we have three or more consecutive PSA increases and, or, PSA between .5-1.

We have those criteria to ensure we have a definitive trend vice an aberration and increase our chances of imaging showing where the activity is and thus enhancing the clinical data used in making our treatment decision.

We do not feel that letting the PSA rise to .5-1 entails any risk in my PCa getting out of control..

There is more and more in the literature about rapid responders , guys whose PSA drops to "undetectable" in the first 6-9 months. The literature says these patients are candidates to come off treatment and generally see longer progression free survival while off treatment. What "undetectable" may not mean is "cured." I am not sure we are yet at the point of advanced PCa being curable. We are changing the treatment landscape to where it may be possible to manage advanced PCa as a chronic disease and use criteria like overall survival, progression free survival...sadly, we know that for some 35k men here in the USA , they die of PCa, not with it.

My medical team knows their task is to make me part of the "with" group. My radiologist off handily made a comment that if I die of a heart attack, the task is complete. A little morbid perhaps but as I pondered her comment, I said yeah...

What is "undetectable?" Depends on the test, assay, measuring equipment and the institution's policies. I am comfortable in saying that in my 12 years undetectable has never been "zero "

The downward trend you cite is encouraging.

Kevin