Yes, it's estimated to be as high as 80%. Even the doctor (Dr. Ablin) who discovered PSA said it should never have been approved as a screening test.
The argument against population-based prostate cancer screening, as I understand it, is that leads to any people having biopsies that turn out to be negative, but yet there is some morbidity associated with the biopsy procedure, including a non-trivial rate of sepsis. But more than that, many of these biopsies will reveal what are probably indolent tumors. And most who are diagnosed with those tumors will go on to get treatment, and will suffer associated side effects and diminished quality of life, all to "cure" a cancer that did not need a a cure. That's the theory, anyway.
A counter-argument is that (1) some people will unnecessarily die if they don't get screened, and (2) the "overtreatment" problem does not require an end to screening, but instead better decision making about treatments, including more use of Active Surveilance for low-risk cancers. I tend to favor that argument, but what do I know...
For those with an enlarged prostate, PSA density can be a useful measure -- that measures total psa divided by prostate size, to account for the fact that larger prostates produce more PSA.
Someone also mentioned the trend in PSA levels being more useful than a single test -- what they refer to as "PSA velocity" -- I agree that is useful, though like lots of things with prostate cancer, you can find different opinions.
I am not a doctor, and none of this is medical advice.
