Cleveland researchers support Stamey’s hypothesis on utility of the PSA test
Posted Jul 06 2010 12:00am
A recent article in Cancer seems to further support Stamey’s contention (published in 2004) that at least in the USA the PSA test has a great deal less value as a screening test for prostate cancer today than it had when it was initially introduced in the 1980s and 1990s.
Bott et al. have compared trends in PSA level, age, and prostate cancer detection among black and white men in Cleveland, Ohio, and the surrounding area during a 16-year period from 1990 to 2006. Their study is based on a retrospective analysis of patient charts and electronic medical records from 5,570 patients diagnosed with prostate cancer (including 911 black patients).
The basic findings of this study are that:
The patients’ mean age at the time of diagnosis did not change in either the white or the black group of patients, “despite what we had believed about the effects of patient education and screening campaigns.”
Prostate cancer detection rates have decreased during the time period studied.
There have been significant decreases in the sensitivity and specificity of PSA as a screening tool over this time period.
Analysis of more recent cases demonstrated a positive predictive value for PSA levels as a predictor for prostate cancer that was only about 50:50 (“comparable to a coin toss”).
Although the relative incidence of specific Gleason scores has remained relatively stable, reporting of prostate intraepithelial neoplasia (PIN) and inflammation has increased.
The authors draw the conclusion that the use of lower PSA thresholds as a criterion for biopsy (e.g., 2.5 ng/ml as opposed to 4.0 ng/ml), promoting PSA testing at a younger age, and increasing efforts to educate the public have not seemed to influence age at time of diagnostic testing. They suggest that this fact may reflect such matters as the perceived value of screening, physician referral patterns, patient compliance, and other sociodemographic issues.
These results are far from surprising to The “New” Prostate Cancer InfoLink, and only go to confirm what Stamey and his colleagues noted in their 2004 paper: that we urgently need a better test that will be much more specific for prostate cancer and that will ideally allow us to dintinguish between clinically significant and indolent disease.