As has been widely reported, the US Preventive Services Task Force has issued a draft recommendation that the prostate-specific antigen (PSA) test should not be used to screen for prostate cancer.
You can read it here (public comments are now being sought). It concludes that “there is moderate certainty that the harms of PSA-based screening for prostate cancer outweigh the benefits”.
The new advice replaces the Task Force’s 2008 recommendation, which had previously recommended against PSA-based screening for prostate cancer in men aged 75 years and older, and had concluded that the evidence was insufficient to make a recommendation in younger men.
However, the Task Force now recommends against PSA-based screening for prostate cancer in all age groups. This recommendation applies to men in the US who do not have symptoms that are highly suspicious for prostate cancer, regardless of age, race, or family history.
The Task Force did not evaluate the use of the PSA test as part of a diagnostic work-up in men with symptoms highly suspicious for prostate cancer. Nor does the recommendation consider the use of the PSA test for surveillance after diagnosis and/or treatment of prostate cancer.
Some extracts from the Taskforce’s draft recommendation statement:
“The common perception that PSA-based early detection of prostate cancer prolongs lives is not supported by the scientific evidence.
The findings of the two largest trials highlight the uncertainty that remains about the precise effect that screening may have, and demonstrate that if any benefit does exist, it is very small after 10 years. The European trial found a statistically insignificant 0.06% absolute reduction in prostate cancer deaths for men aged 50 to 74 years, while the U.S. trial found a statistically insignificant 0.03% absolute increase in prostate cancer deaths. A meta-analysis of all published trials found no statistically significant reduction in prostate cancer deaths.
At the same time, overdiagnosis and overtreatment of prostatic tumors that will not progress to cause illness or death are frequent consequences of PSA-based screening. Although about 90% of men are currently treated for PSA-detected prostate cancer in the United States—usually with surgery or radiotherapy—the vast majority of men who are treated do not have prostate cancer death prevented or lives extended from that treatment, but are subjected to significant harms.
… While the USPSTF discourages the use of screening tests for which the benefits do not outweigh the harms in the target population, it recognizes the common use of PSA screening in practice today and understands that some men will continue to request and some physicians will continue to offer screening.
An individual man may choose to be screened because he places a higher value on the possibility of benefit, however small, than the known harms that accompany screening and treatment of screen-detected cancer, particularly the harms of overdiagnosis and overtreatment. This decision should be an informed decision, preferably made in consultation with a regular care provider.
No man should be screened without his understanding and consent; community-based and employer-based screening that does not allow an informed choice should be discontinued.
…The mortality benefits of PSA-based prostate cancer screening through 10 years are small to none, while the harms are moderate to substantial. Therefore, the USPSTF concludes with moderate certainty that PSA-based screening for prostate cancer, as currently utilized and studied in randomized, controlled trials, has no net benefit.”
More reading: The US health journalism watchdog Gary Schwitzer describes this recent New York Times magazine piece, Can Cancer Ever Be Ignored?, as “one of the best pieces on cancer screening that I’ve seen”.
Update, 12 Oct.
• More analysis from the Foundation for Informed Medical Decision Making, including a video for helping men to make sense of it all.
• H. Gilbert Welch, a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice, and a co-author of Overdiagnosed: Making People Sick in the Pursuit of Health, says that screening is like gambling because there are winners and losers. He writes in the New York Times:
“Personally, as a 56-year-old man, I choose not to be screened for prostate cancer (and, were I female, I believe I would choose not to be screened for breast cancer). Some of my patients have made the same choice, while others choose to be screened. That’s O.K., because there is no single right answer.
Screening is like gambling: there are winners and there are losers. And while the few winners win big, there are a lot more losers.”