PSA level not a good predictor of prostate cancer, study finds
Tuesday, March 1, 2011
WASHINGTON (AP) — A rising PSA level isn’t such a good predictor of prostate cancer after all and can lead to many unnecessary biopsies, says a large new study.
Most men over 50 get PSA blood tests, but they’re hugely problematic. Too much PSA, or prostate-specific antigen, only sometimes signals prostate cancer is brewing — it also can mean a benign enlarged prostate or an infection. And screening often detects small tumors that will prove too slow-growing to be deadly. Yet there’s no sure way to tell in advance who needs aggressive therapy.
On the other hand, some men have cancer despite a “normal” PSA count of 4 or below. So for PSAs that are rising, yet still in the normal range, some guidelines urge doctors to consider a biopsy.
How quickly the PSA number rises is something “that patients and doctors worry a lot about,” said Dr. Andrew Vickers of Memorial Sloan-Kettering Cancer Center. “Men show up here with a PSA of 2 and we say, ‘Why are you here?’ And they say, ‘Well, I used to be a 1 and my doctor’s worried. Am I going to die?”’
So Sloan-Kettering researchers studied whether considering PSA velocity adds value to the biopsy-or-not decision in those otherwise low-risk men — and concluded it doesn’t.
“This is a really important study,” said Dr. Otis Brawley of the American Cancer Society, who wasn’t part of the research. “A lot of doctors are going to stop looking at a PSA rise of 1 and ordering biopsies.”
Vickers’ team tracked 5,519 men who’d taken part in a huge prostate cancer prevention study and who’d received a biopsy at the study’s end regardless of their PSA level.
Just having a rising PSA — if nothing else was considered — was associated with a slightly higher risk of having cancer, although not the more worrisome aggressive kind. But the PSA level alone, not its rise, was a much better predictor of a tumor, reported Vickers, a statistician who specializes in prostate cancer.
Focusing on PSA’s rise instead triggered many more biopsies, with close to 1 in 7 men who would get one, concluded the study, published in the Journal of the National Cancer Institute.
That compares with 1 in 20 men who are biopsied for a high PSA level alone, noted Dr. Grace Lu-Yao of the University of Medicine and Dentistry of New Jersey in an accompanying editorial.
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