Panel: Don't Get PSA Prostate Cancer Screen
Harm Outweighs Benefit of Routine Prostate Cancer Screening, Task Force Says
PSA Test: Clinical Trials
A bone of contention between the USPSTF and its critics is how to interpret the two main clinical trials that looked at whether PSA screening prevents prostate cancer deaths.
The European study dubbed the ERSPC found that a man's odds of dying of prostate cancer are 21% lower if he's offered routine PSA screening. Overall, one cancer death was prevented for every 936 men screened.
The large U.S. clinical trial dubbed the PLCO found that screened men tended to be more likely to die of prostate cancer. That's probably a statistical blip, as the test isn't likely to cause cancer deaths. But it does make it clear that the study found no indication of a benefit, LeFevre says.
Taking the two trials together, the USPSTF concluded that PSA screening simply doesn't prevent enough cancer deaths to make it worth the harms of unnecessary treatments.
Critics take a different view. They note that about half the supposedly unscreened men in the U.S. study actually had one or more lifetime PSA tests. That, they say, contaminates the results. Moreover, men in the study did not get prompt biopsies after a troubling PSA test.
"The bottom line is that the task force has made a recommendation against PSA screening based primarily on data from the U.S. trial, which unfortunately is not reliable," D'Amico says.
PSA Test: Controversial Issues
Interpretation of clinical trials isn't the only issue critics take with the USPSTF recommendation:
- The critics say that prostate cancer deaths have dropped 40% since PSA screening began. But LeFevre notes that this decline began years before PSA testing caught on -- and that there have been similar declines over the same time period in cancers for which there are no screening tests. D'Amico says that since PSA screening, there's been an even steeper drop in prostate cancer deaths.
- The critics say that the clinical trials have followed men only for about 10 years, too little time to see the full benefit of screening. But LeFevre says that in 10 years there should at least be a clear signal that screening is saving lives -- as has been seen with screening for colon and breast cancer. D'Amico says there was indeed such a signal, but the USPSTF didn't get it.
- The critics say the task force should at least recommend PSA screening for men at higher risk of prostate cancer, particularly African-American men and men with a family history of prostate cancer. But LeFevre says there's no clear evidence that PSA screening actually saves lives in these populations.