March 14, 2012 -- The odds of dying from prostate cancer are 21% lower 11 years after men are offered routine screening with the controversial PSA blood test, European researchers find.
Those odds go down 29% if you only count men who actually got screened in the huge European Randomized Study of Screening for Prostate Cancer, or ERSPC. The study enrolled 182,160 men ages 50 to 74 in eight European countries.
The findings strengthen confidence in earlier results reported in 2009, says study leader Fritz H. Schroder, MD, PhD, professor of urology at the Netherlands' Erasmus University.
"While we don't understand the downside completely, the upside of screening has improved with this report," Schroder tells WebMD. "We more definitively show there is an advantage in screening for prostate cancer, and that the reduction in prostate cancer mortality for those men who are screened amounts to 29%."
Despite this benefit, Schroder says the findings do not mean that all men should get regular PSA tests.
"The difficulty is we still haven't made any progress in avoiding the overdiagnosis and overtreatment [of PSA-screened men], which is the main factor impacting their quality of life," he says. "There is no way at this moment to come to a population-based screening policy anywhere in the world. Men must still be confronted with the need to make their own decisions."
Overdiagnosis is the detection and treatment of a latent or slow-growing cancer that would never kill. Schroder and colleagues estimate that half of screening-detected prostate cancers are overdiagnosed. They calculate that 936 men must be screened for 11 years, and 33 cancers detected, to avert a single cancer death.
The cost of overdiagnosis is high, says University of Toronto researcher Anthony B. Miller, MD.
"We know the complications of screening," he says. "One of the major ones is that you find latent prostate cancers -- ones that are not likely to progress, will never kill an individual, would not cause that individual symptoms -- yet if you find them you have to treat them. The consequences of treatment can be quite severe. Men become impotent and incontinent. Both in the U.S. and European trials, deaths have occurred as a result of treatment for prostate cancer."
The European findings are in contrast to those from the U.S. Prostate, Lung, Colorectal, and Ovarian (PLCO) study. Miller says the U.S. study "shows absolutely no indication of a benefit" even after 13 years of routine PSA screening.
Miller, one of the PLCO investigators, is critical of the European study. In an editorial accompanying the Schroder report, he suggests that PSA-screened men were more likely to be treated for prostate cancer at academic centers, where they got more state-of-the-art treatment.