Experts: PSA Test Still Valuable for Prostate Cancer Screening
By E.J. Mundell, HealthDay Reporter
SATURDAY, Nov. 13 (HealthDayNews) -- Earlier this fall, the researcher who first identified the prostate-specific antigen (PSA) blood test -- used for nearly two decades to screen men for prostate cancer -- announced the test had become "all but useless."
Writing in the October issue of the Journal of Urology, Stanford University's Dr. Thomas Stamey said the test is now more likely to spot benign prostate enlargement or very slow-moving malignancies than "significant," aggressive cancers, raising risks for misdiagnosis and unnecessary surgeries.
The news left millions of older American men confused about whether their annual PSA test was worth it, and whether its results could be trusted.
But according to experts representing two leading medical groups, rumors of the demise of the PSA test may be premature.
Dr. Durado Brooks, director of prostate and colorectal cancer at the American Cancer Society, noted that "Dr. Stamey's article is countered by a wealth of other literature, so there's a lot of dispute right now among experts as to the level of value PSA testing offers."
He believes PSA screening remains "a useful test, in terms of detecting prostate cancer in its early stage."
The PSA test -- which measures blood levels of a compound secreted at higher levels as prostates enlarge -- may well be a victim of its own success. Experts generally agree that when the test was first put into widespread use in the 1990s, it picked up a lot of advanced cancers that had previously been missed.
But as annual screenings have become more commonplace, PSA screening is now detecting much smaller cancers -- many of them slow-growing and worthy of "watchful waiting" rather than more radical prostate-removing surgery.
What's needed, according to Brooks, are improvements to the existing PSA test "so that we can differentiate those 'bad actors' -- prostate cancers that are more likely to be aggressive and to cause problems -- from the indolent [slow-growing] tumors that are often found."
Dr. J. Brantley Thrasher is chairman of urology at the University of Kansas Medical Center and a spokesman for the American Urological Association. He agreed with Brooks that the PSA test needs to be refined, not discarded.
"The fact of the matter is that death rates from prostate cancer have dropped precipitously from the 1990s," he said, although there's no clear evidence that decline is due to PSA-linked early detection.
"What we're trying to do now is find better markers, tweaking PSA to make it better," he said.
"What bothers me a little bit, especially in the lay press, is that when we start to see a little controversy around something like PSA screening, people out there will say 'Well, there's no use for PSA, don't even get one,'" he said.
"Then I worry that we'll go back to the situation we had 10 or 15 years ago, where we are seeing a lot of advanced-cancer patients walking through the door, crippled with bony metastases because they're not finding it till it's very late, and we don't have anything to offer them."
Thrasher pointed out that, despite better early detection, prostate cancer is still the second leading cause of cancer death in men, killing more than 30,000 American males each year.
According to both Thrasher and Brooks, Stamey's dismissal of the PSA test came as no real surprise, since debate has simmered among urologists and cancer specialists for years as to the exam's continued efficacy in spotting cancers worthy of aggressive treatment.
"It's always been a controversial issue," Thrasher said, "because PSA can be elevated for a number of reasons besides cancer," including the benign prostate enlargement that occurs naturally as men age.
The challenge for researchers is to find better blood markers, to make the test more specific, Thrasher said. "Almost every quarter I'm seeing literature coming out with new molecular markers," he said. "I'm truly convinced that we're going to come up with something that -- either combined with PSA, a PSA [variant], or by itself -- will be better."
In the meantime, the American Cancer Society continues to recommend that doctors offer annual PSA screening, plus a digital rectal exam, to all normal-risk male patients over 50 years of age.
According to Brooks, the challenge for patients is to "understand the benefits and the limitations of the PSA test and decide for themselves, in consultation with their physicians, exactly what they want to do, and whether they want to be tested or not."
More information
To learn more about prostate cancer screening, visit the American Cancer Society (www.cancer.org ). 
SOURCES: Durado Brooks, M.D., M.P.H., director, prostate and colorectal cancer, American Cancer Society; J. Brantley Thrasher, M.D., chairman, department of urology, University of Kansas Medical Center, Kansas City; October 2004 Journal of Urology
Copyright � 2004 ScoutNews, LLC. All rights reserved.
|
