PSA Test Cuts Prostate Cancer Deaths -- at a Cost
European PSA Study: Screen 936 Men, Save 1 Cancer Death
European PSA Study vs. U.S. PSA Study continued...
And even though the screened men were less likely to die of prostate cancer, death from any cause was just as likely in screened as in unscreened men.
Schroder says the PLCO study has its own flaws -- not least of which is that about half the men in the group that was supposed to be unscreened actually had a PSA test before the study began. This, he says, means that many men with hidden, aggressive cancers were never enrolled in that group.
Indeed, in the European study, three-fourths of the screened men who died of prostate cancer had their disease detected on first screening.
Both Schroder and Miller agree that while they complement each other in some ways, the two large PSA studies have many differences. These include:
- European men were screened only once every four years (every two years in Sweden); U.S. men were screened every year.
- In Europe, screened men got prostate biopsies when their PSA level was 3 ng/mL. In the U.S., the PSA cutoff was 4 ng/mL.
- In the European study, 13% of screening tests were false positives (no cancer detected on biopsy). The false-positive rate in the U.S. study was 7%.
- The European PSA study enrolled about twice as many men as the U.S. study.
- Overdiagnosis rates were about 50% in the European trial, but 17% to 30% in the U.S. trial.
The PSA Test: Advice to Men
Despite their very different takes on the two PSA studies, Schroder and Miller are in remarkable agreement about the lessons men should take from them.
Both agree that the U.S. Preventive Services Task Force is correct to say that men should not routinely be given PSA tests.
But Schroder argues for a more nuanced approach -- the one advocated by the American Cancer Society. That advice is for doctors to sit down with each individual patient to give him a thorough explanation of both the risks and benefits of regular PSA tests.
Unfortunately, Schroder says, doctors are more or less on their own. What they need is research that will tell them the most effective way to help men make this important decision.
"The time has come to develop and validate balanced information on the advantages and disadvantages of PSA screening for the man on the street," he suggests.
The Schroder report, and Miller's editorial, appear in the March 15 issue of the New England Journal of Medicine.