Earlier Start, Stop for PSA Testing?
Prostate Cancer Screening May Start Earlier -- and Stop Sooner
Early PSA Test -- and Then No More? continued...
In their first look at the data, the researchers found that a single PSA test before age 50 predicted low or high risk of prostate cancer. Now they report that a single PSA test before age 40 predicts prostate cancer risk.
"We are seeing that low PSA values are associated with low future risk of prostate cancer," Lilja says. "The median PSA level in this population of men with low long-term risk is around 0.6 ng/mL."
The researchers hoped to find a time point when the prostate cancer process starts. But that effort has not yet been successful.
"So far we have not been able to see an age where we don't see the signal," Lilja says. "But now we know we can identify individuals who, in the future, are quite unlikely to benefit from further testing and intervention. What that means for PSA screening guidelines is not yet known. And how often a low-risk man will need PSA testing, we don't know."
However, AUA spokesman Ira D. Sharlip, MD, clinical professor of urology at the University of California, San Francisco, says the AUA committee responsible for these guidelines is taking a hard look at the Lilja team's data. Current AUA recommendations call for men to start PSA screening at age 50 if they are not at high risk, because relatively few such men get prostate cancer before then.
"The PSA guideline document that AUA has was written in 2000; it is being updated now," Sharlip tells WebMD. "On the basis of this study, there is a possibility they might revise it to age 40."
Can PSA Screening Stop at 75?
Since prostate cancer takes a while to develop -- and even longer to become deadly -- there's obviously an age beyond which prostate cancer screening will result in far more risk than benefit. But what's that age?
Sharlip says the rule of thumb is to stop PSA screening when a man's probable life expectancy is less than 10 years.
"With good life expectancy, a man is at risk of prostate cancer and death if he doesn't get his PSA tested," Sharlip says. "But what about a man with rising PSA that's still at a marginal level? That is exactly the situation that is poorly defined."
Help comes from Anna Kettermann and colleagues at Johns Hopkins University. Kettermann and colleagues collected data from 849 men participating in the Baltimore Longitudinal Study of Aging.
Eighteen of the men died of prostate cancer. Not even one had a PSA under 3.0 ng/mL. Moreover, men with PSA levels this low had virtually no chance of serious prostate cancer or PSA levels that later soared.
"We wanted to look for the men who have PSA values that will never bring them to the condition that prostate cancer will kill them," Kettermann tells WebMD. "If a man is old and has a low PSA and a history of low PSA, he is unlikely to develop high-risk disease."