On November 7, Linda wrote:

A PSA test result that is =/< 0.05 ng/mL is "undetectable" and is a
desirable result. See, _A Primer on Prostate Cancer_ 2nd ed. by med onc
and PCa specialist Stephen B. Strum, MD, and PCa warrior Donna Pogliano
at page 144.

Small amounts of PSA are expressed elsewhere than the prostate. That is
why ADT often includes meds that block the binding to PSA receptors of
PSA from such sources.

Regards,

Steve J

My understanding, Linda, is that the urologist has in mind a certain PSA
level that he or she believes is unlikely to be a problem.  Part of it is
that PSA numbers are subject to a certain fluctuation from time to time,
depending on many variables.  The "best" determination is a trend or average
as observed for months or, in the early cases, a few years.  Laboratory
equipment itself and the degree of effort that lab technicians or doctors
require from a test may be significant.  I don't know, but I imagine a PSA
figure that goes to two or more decimal places is more complex and more
expensive than one at only one decimal place.  The figure gives the patient
an idea that his test is somehow more or less precise and hence more or less
accurate than one reported at <0.1 or 0.0.  In my own case, my reports,
taken at 9-month intervals now, come back as "undetectable."  I know that
doesn't mean 0.0000, but it means a satisfactorily low value and neither my
oncologist-surgeon nor myself are concerned; in fact, we are both highly
encouraged (after about four years).

Far more important today is the rate of rising PSA.  There's an interesting
article in the Wall Street Journal today that mentions that.  So that you
won't think I'm making this up, I quote from the WSJ, quoting, in turn, from
Dr.H. Ballentine Carter, professor of urology/oncology at John Hopkins:  "A
50-year-old man with a PSA of 4 will likely be told that he needs a biopsy.
However, if that man at the age of 40 had a PSA of 2, the 10-year trend
suggests that he likely doesn't have cancer or at least not an aggressive ca
ncer."

In short, Dr. Carter advises that a man with a score above 0.6 at age 40
should be checked every two or three years.  The figures obtained in this
way are indicative of the rate of increase and level of concern.  The data
show that a man whose PSA rises by 0.35 ng/ml or more each year will see a
fivefold increase in the risk of dying from prostate cancer in the next two
to three decades.

There's more, but I've already answered questions that you hadn't asked.
Watch this thread for more informative replies.

Ken Bland

The test isn't perfect and there is some measurment error.   So they
can't really confirm a measurement of zero.   In addition, there are
other tissues in the body which produce very small amounts of PSA.

There is also sometimes confusion in that the actual result is 'less
than 0.02' and this is reported as 0.02.

In any case, such a value means that PSA is undetectable for all
practical purposes, so you shouldn't worry about it.

Just thought that I would weigh in. Undetectable PSA varies with the doctor
and in how it is used. For example on each of the following PSA tests I was
told at some point that it was undetectable:

0.2
0.1
less than 0.1

A lot has to do with the manufacture of the antigen elsewhere in the body
not associated with the prostate.

I realize that this will drive some batty, but so be it. :)

That's great!!!  Especially more than a year after RT.