Value of PSA screening test questioned
■ The test represents a significant decision dilemma for both patients and physicians. Some physicians believe it should be an annual ritual. Others aren't so sure.
By Victoria Stagg Elliott — Posted Oct. 11, 2004
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G. Stephen Nace, MD, a general internist in Peoria, Ill., often ends up talking prostate-specific test results on Sundays after church. Men from the congregation come up to him and tell him their most recent scores from this common prostate cancer screening method.
"Guys talk about it," said the assistant professor of clinical medicine at the University of Illinois College of Medicine. "But I don't think many patients really appreciate the depth of the question and the issues involved. For most patients, it's just a blood test."
The test is one of the more controversial in medical circles, and this month, even one of the researchers who carried out much of the groundbreaking work to create it questioned whether it should be used at all.
"The PSA era is over in the United States," said Thomas Stamey, MD, professor of urology at Stanford University School of Medicine and lead author on the landmark paper in the Oct. 8, 1987, New England Journal of Medicine suggesting that rising PSA levels could be useful to detect and monitor prostate cancer.
Dr. Stamey's declaration came as part of his more recent paper published in the October Journal of Urology that offered a very different conclusion. In this study, he and his team analyzed tumors from more than 1,000 radical prostatectomies over the past 20 years. They determined that PSA testing was discovering smaller and smaller tumors that were less likely to be deadly. Thus, the conclusion: PSA levels are more indicative of whether the prostate is enlarged than if it is cancerous and needs to be treated.
"Our study raises a very serious question of whether a man should even use the PSA test for prostate cancer screening any more," Dr. Stamey said. "Our job now is to stop removing every man's prostate who has prostate cancer. We originally thought we were doing the right thing, but we are now figuring out how we went wrong. Some men need prostate treatment, but certainly not all of them."
Dr. Stamey's latest article supports the opinions of those physicians concerned that increased PSA test screening is leading to overtreatment of cancers that men are more likely to die with than of.
"This paper adds to a growing body of literature that seriously questions the use of PSA testing," said Timothy J. Wilt, MD, MPH, professor of medicine and a general internist at Minneapolis Veterans Affairs Center for Chronic Disease Outcomes and Research. "The fundamental point remains that it is still not known whether early detection with PSA testing reduces disease-specific morbidity or mortality. It's also not known whether early treatment improves length or quality of life."
But physicians who are hesitant about PSA testing -- a position consistent with the U.S. Preventive Services Task Force recommendations that say there is insufficient evidence to recommend it -- still find themselves in a difficult fix. The test is enormously popular among patients, even though its possible benefits are still controversial. But helping a patient sort through the debate and make a decision is a time-consuming challenge.
"I will go over the pros and cons, what's known and what's not known," Dr. Nace said. "But it depends so much on the individual patient."
It's also very likely that widespread PSA testing has benefited some men. It's just not clear who.
"It's helped some men, but we don't know in advance which men it will help," said Julie Mitchell, MD, assistant professor of medicine and a general internist at the Medical College of Wisconsin in Milwaukee. "It has also done some bad."
Disagreement in the ranks
Prostate cancer experts, many of whom are lobbying for annual screening of men past a certain age, responded angrily to Dr. Stamey's paper and expressed apprehension that some men might not come forward because of it.
"He's sending out a very unfortunate message," said William J. Catalona, MD, professor of urology and director of the clinical prostate cancer program at the Robert H. Lurie Comprehensive Cancer Center at Northwestern Memorial Hospital in Chicago. "It's wrong, and if patients give it credibility, it could cause some men to die a horrible death from prostate cancer."
Experts said finding ever-smaller tumors was evidence that population-wide screening was performing an effective job of improving prostate cancer outcomes, and that the adverse effects from treatment were worth the benefit of finding and detecting this form of cancer early.
"We got to a good place because of PSA screening," said Mark Garzotto, MD, associate professor of urology at the Oregon Health and Science University School of Medicine and a staff researcher at the Portland VA Medical Center. "Do we abandon the PSA because it's effective?"
But experts also agreed with Dr. Stamey's notion that the PSA test is far from the perfect screener and that a better test is needed to detect which prostate cancers are most likely to kill. Many are already using the rate of change in PSA numbers over time rather than the numbers themselves, and new tests are on the horizon.
"This data certainly does not signify the end of the use of PSA," said Michael J. Manyak, MD, chair of the Dept. of Urology at George Washington University. "We're going to see an evolution, not only in the use of PSA as it is now, but an evolution in the use of the 'sons of PSA,' if you will."