New Debate on Prostate Cancer Screening
U.S. Study Shows PSA Test Doesn't Save Lives; European Study Shows Modest Benefit
March 18, 2009 -- Interim findings from an eagerly awaited ongoing government study show no evidence of a survival benefit associated with aggressive screening for prostate cancer using the prostate specific antigen (PSA) test.
More prostate cancers were detected over an average of seven years of follow-up among men who had regular PSA testing in addition to digital rectal exams compared to usual care, which could have included screening. But the increase in prostate cancers did not translate into fewer deaths from the disease.
The findings are certain to add to the controversy surrounding the value of PSA testing for prostate cancer screening, and the debate about whether current screening practices have led to overdiagnosis and overtreatment of prostate cancer.
The study, funded by the National Cancer Institute was published online ahead of publication in the March 26 issue of the New England Journal of Medicine.
"What this report tells us is that there may be some men who are diagnosed with prostate cancer and have the side effects of treatment, such as impotence and incontinence, with little chance of benefit," NCI director John E. Niederhuber, MD, says in a news release.
"Clearly, we need a better way of detecting prostate cancer at its earliest stages and as importantly, [we need] a method of determining which tumors will progress."
Screening Beneficial in European Study
To add to the confusion, findings from a major European trial appearing in the same issue of the New England Journal of Medicine did show a modest, 20% survival benefit associated with PSA screening in men followed for an average of nine years.
Both the U.S. and the European studies will be presented this week at the European Association of Urology annual meeting in Stockholm, Sweden.
For every 10,000 men screened with PSA over a nine-year period in the European trial, seven fewer deaths from prostate cancer were reported.
But the European researchers estimated that 48 additional men whose cancers were detected as a result of screening would need to be treated to avoid one prostate cancer death.
That compares with about 10 additional treatments among women screened with mammography needed to prevent one death from breast cancer, prostate cancer screening researcher Michael J. Barry, MD, of Harvard Medical School tells WebMD.
Barry, who wrote an editorial that appeared with the studies, adds that the new research helps to quantify the benefits and risks associated with PSA screening.
"When you look at the two trials together it becomes clear that the benefits, in terms of survival, are fairly modest," he says. "They are similar to what we see with mammography, but in my opinion it comes at a much higher price in terms of overdiagnosis and overtreatment."