March 31, 2011 -- A study from Sweden raises new questions about the value of screening average-risk men for prostate cancer.
In the study, screening did not significantly reduce prostate cancer deaths over two decades of follow-up, but it did result in the detection of more cases of the cancer and more treatment.
The study is not as large as several other recent trials suggesting that routine screening leads to the over-detection and overtreatment of prostate cancer, but it is the longest.
Starting in 1987, some study participants received routine screening for prostate cancer while others did not. Twenty years later, the two groups had similar prostate cancer death rates.
“We found no survival advantage for screening, but this may have been influenced by the fact that the screening test we used when the trial started is not as sensitive as the tests we use today,” study researcher Gabriel Sandblom, MD, of Stockholm’s Karolinska Institute, tells WebMD.
PSA Screening Debate
The men in the screening study group did not receive prostate specific antigen (PSA) blood testing until their third or fourth screenings.
PSA is now the screening method of choice, but it remains controversial.
The American Cancer Society stopped recommending routine PSA screening more than a decade ago. Last year the group came out even more strongly against routine testing, stating that men should not be screened without first discussing the risks and limitations of screening with their doctors.
Two major studies published in 2009, one from the U.S. and another from Europe, added to the concerns about the PSA screening.
The U.S. trial, supported by the National Cancer Institute, failed to show a reduction in prostate cancer deaths associated with PSA screening over an average of seven years of follow-up.
The European study showed a modest reduction in prostate cancer deaths associated with screening, but the researchers concluded that an estimated 1,400 men would have to be screened and 48 men would have to be treated to prevent one death from prostate cancer.
A separate analysis involving Swedish participants in the European trial lowered that number to 293 men screened and 12 men treated to prevent one death.
“The 48 number is probably an overestimate and it is not clear if the 12 is an underestimate,” ACS Director of Prostate and Colorectal Cancers Durado Brooks, MD, MPH, tells WebMD. “What we can say is that there is significant over-diagnosis and overtreatment associated with screening.”
Prostate cancer is most often treated with surgery and radiation, which can result in erectile dysfunction and bladder and bowel incontinence.
Screening for Prostate Cancer
The newly published study included close to 1,500 Swedish men randomly selected for prostate cancer screening every three years from 1987 to 1999 and about 7,500 men who were not screened.
Digital rectal examinations were the only screening method used until 1993, when PSA testing was added to the screening protocol.
Between January 1987 and the end of 1999, 85 screened study participants (5.7%) and 292 men who were not screened (3.9%) received a diagnosis of prostate cancer.
The tumors detected in the screening group tended to be smaller and more localized than those found in the men who were not screened. But the death rate did not differ significantly between the two groups.
Sandblom says PSA testing is beneficial for men with symptoms suggestive of prostate cancer or men with a high risk for the disease due to family history.
He agrees that the test is not appropriate for other men unless they fully understand the benefits and limitations of screening.
Because some men in the study did not have a PSA test at all and none had more than two tests, Brooks says the study adds little to the PSA debate.
“We know from other studies that PSA is far from a perfect tool,” he says. “While it has certainly had some value for some men, questions remain about its long-term impact on whether or not men die from prostate cancer.”