Studies Ask: Which Men Benefit Most From Prostate Cancer Screening?

BY Lea Winerman  September 15, 2010 at 4:05 PM EDT

Two studies published this week suggest that a single prostate cancer screening test performed at a relatively young age could help men and their doctors decide whether or not they would benefit from regular follow-up screening.

For years, researchers have been debating whether annual tests that screen for prostate cancer might do more harm than good. The PSA test looks for an elevated level of a marker called prostate specific antigen in the blood. PSA is a protein made only in the prostate, and if a large amount of it escapes into the bloodstream, it can be a sign of a problem with the prostate, including but not limited to cancer.

“We think that if we said to men ‘You, Mr. Smith, don’t have to come back. But you, Mr. Jones, we don’t say this to everyone, but you really are at high risk’ — that guy might come back.”
Memorial Sloan-Kettering Researcher Andrew Vickers

The screening tests undoubtedly catch cancers early and save some lives through early detection. The problem is, however, that many prostate cancers are slow-moving and non-aggressive, and would never have bothered the patient had they not been caught by the screening test. So screening can lead to anxiety and overtreatment for a disease that never would have harmed the patient anyway.

Last spring, a pair of studies in the New England Journal of Medicine added more fuel to the debate. One study, by American researchers, found that regular screening did not reduce death rates from prostate cancer. A European study, meanwhile, found that regular screening did reduce death rates by about 20 percent, but that about 50 men needed to be to be treated in order to prevent one death.

But two new studies published this week suggest that doctors should move away from an all-or-none approach to regular screening, and instead target screening to those patients most likely to benefit from it.

In one study, published Tuesday in the British Medical Journal, researchers at Memorial Sloan-Kettering Cancer Center in New York found that men who had a low PSA level at age 60 were very unlikely to die from the disease by age 85. Conversely, men with high PSA levels at age 60 had a much greater chance of developing fatal prostate cancer.

The researchers followed men who were born in Sweden in 1920 or 1921, and had blood samples frozen as part of a research project called the Malmo Preventive Project in Malmo, Sweden. The men were followed until age 85.

Memorial Sloan-Kettering Cancer Center researcher Andrew Vickers and his colleagues found that the 25 percent of the men with the highest PSA levels at age 60 — above 2 nanograms per milliliter — comprised 90 percent of those who eventually died from prostate cancer.

Vickers says that the findings suggest that the question “isn’t whether screening works, but how to make it work better.”

“Current guidelines say, roughly speaking, all men should come back every year, or couple of years,” Vickers says. “One of the interesting things about that is that only about half of men actually do. We think that if we said to men ‘You, Mr. Smith, don’t have to come back. But you, Mr. Jones, we don’t say this to everyone, but you really are at high risk’ — that guy might come back.”

Another study published Monday in the journal Cancer found remarkably similar results. Researcher Pim Van Leeuwen of Erasmus University Medical Center in the Netherlands and his colleagues looked at the records of more than 85,000 men ages 55 to 74 in the Netherlands, Sweden, Finland and Northern Ireland. They found death rates were highest among men who had a high PSA level at the beginning of the study. For those with a beginning PSA level of less than 2 nanograms per milliliter, 24,642 men had to be screened for cancer to save one death. For those with a PSA above 10, the rate was 133 screenings to save one death.

Otis Brawley, the Chief Medical Officer of the American Cancer Society, said it’s significant that both papers, produced independently, found such similar results.

“They’re both trying to figure out which men are going to get the kind of cancer that isn’t going to kill them,” Brawley says.