THURSDAY, March 31 (HealthDay News) -- A 20-year study from Sweden suggests that screening for prostate cancer does not substantially reduce the risk of death from the disease.

On the other hand, a good many men might receive false-positive results and overtreatment, adding an element of risk to widescale screening, the researchers report in the March 31 online issue of the BMJ.

"In the light of our findings, I would say that the benefit from screening is not sufficient to support mass screening," said study author Dr. Gabriel Sandblom, an associate professor at the Karolinska Institute in Stockholm.

"However," added Sandblom, "the study was initiated more than 20 years ago, when PSA [prostate specific antigen testing] was not available and the treatment of localized prostate cancer was not as effective as it is today. I would thus not categorically advise against PSA testing based on an individual decision from a man who feels concern about prostate cancer."

This advice is not out of line with recently updated guidelines on prostate cancer screening from the U.S. government. The recommendations, issued in 2008, take a dim view of prostate cancer screenings at any age for healthy men and flatly recommend against them entirely for men over 75.

The American Cancer Society has also recently revisited the issue of prostate cancer screening.

"A little over a year ago, the American Cancer Society revised its guidelines, which reinforced the message that men need to be informed that there are known benefits, but also limits, to PSA screenings," said Dr. Durado Brooks, director of prostate and colon cancer at the American Cancer Society. "The American Cancer Society does not encourage nor discourage prostate cancer screenings."

This new study does carry with it several significant weaknesses, Brooks added. In particular, because of the timing and design of the study, most men really only received one and, at most, two PSA tests.

"At best, this is a study of one or two PSA tests in men in their late 50s and early 60s," he said.

For the study, researchers looked at all men in the Swedish city of Norrkoping who were between the ages of 50 and 69 in 1987, a total of 9,026 men.

Of these, 1,494 men were screened for prostate cancer -- first with a digital rectal exam (DRE) and, starting in 1993, with both DRE and PSA tests -- every three years.

In 1996, only men aged 69 or under were screened.

The remaining 7,532 men did not undergo screening and served as a comparison group.

The mortality rate for men who underwent screening was not significantly different from that in the control group, although tumors in the screened group tended to be smaller and more localized.

Commenting on the study, Dr. Chad LaGrange, an assistant professor of urology at the University of Nebraska Medical Center in Omaha, said he believes the findings actually add "much more uncertainty" to an already complex problem.

With more and more studies on the subject, "guidelines have become vague recommendations," he said. "We don't really have any good rules anymore."

The bottom line: "It's not just as simple as PSA screening either works or it doesn't. Patients should talk about it with their doctor," LaGrange said. "PSA testing shouldn't be just a reflex anymore."

But the good news hidden here is that the number of prostate cancer deaths continues to decline, whether it be better screening or better treatment, he said. "We're doing something right," LaGrange stated.

More information

The American Cancer Society has more on getting tested for prostate cancer.