By Ray Downs
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PSA (short for prostate-specific antigen) screens have become nearly as common as blood-pressure tests when men over 50 visit their doctors. But that doesn't mean the cancer-detection tests popularized by Dr. William J. Catalona are accurate. Even supporters of PSA testing acknowledge that screenings often miss tumors or ring false alarms. Critics say PSA tests can lead to unnecessary biopsies and surgeries that may cost a man his ability to have intercourse or control his bladder. The medical community is divided as to whether PSA tests should be a part of routine checkups.
The American Urological Association recommends universal PSA screening for men over 50 years of age. The American Cancer Society says men should be given the option but stops short of advocating mass testing. The National Cancer Institute and the Centers for Disease Control and Prevention, both arms of the federal government, don't recommend routine screening. Neither does the American College of Physicians, a medical society that includes 115,000 physicians and medical students, or the U.S. Preventive Services Task Force, a panel of healthcare professionals set up by the federal government to assess whether immunizations and other kinds of healthcare practices aimed at preventing diseases are worthwhile.
High PSA levels may indicate nothing more serious than a benign enlargement of the prostate. Some research has shown that avid bicyclists are prone to high PSA levels -- presumably triggered by hours spent on narrow bicycle seats -- and some doctors advise patients to avoid sex before being tested because ejaculation can raise PSA levels. Indeed, Beckman Coulter, Inc., a San Diego company that makes PSA tests, recently paid for a study that found fewer than half of 1,091 men who underwent biopsies based on PSA screens actually had cancer.
A man faced with a high PSA level faces a difficult choice. Once cancer spreads outside the prostate, it is almost always fatal, so the only hope is to find tumors while they're still confined to the gland. But not all cancers are created equal. Research and experience have shown that only a fraction of prostate tumors are dangerous, and many are so small that catching them with a biopsy is the equivalent of hitting a bulls-eye on a dart board from twenty feet away. Unlike lung cancer, which kills virtually all of its victims, most men with prostate tumors will die from other causes. The trick, then, is to detect the cancer early and figure out whether it's a potential killer.
"There's no blood test that can differentiate cancer from non-cancer," says Dr. Thomas A. Stamey, a Stanford University researcher. "We've used PSA as an excuse to biopsy prostates. We would do just as well if we simply went out and said, 'Well, let's take everybody with blue eyes over the age of 50 and biopsy him.' You would probably get the same amount [of cancer]."
In a 2001 article published in Urology Times, Stamey wrote much the same thing in a public clash with Catalona about the efficacy of PSA testing. "Dr. Catalona and I have access to the same data, but we interpret it very differently," Stamey wrote. In an accompanying response, Catalona called Stamey's conclusions misleading and cited academic papers that credited PSA tests for helping reduce the death rate from prostate cancer during the late 1990s.
Stamey says a man diagnosed with prostate cancer shouldn't necessarily rush to a surgeon while updating his will. He cites a study done by a pathologist from Wayne State University in Detroit who dissected prostates of relatively young men who died violent deaths on the street.
"What he found is that men in their twenties dying on the streets of Detroit, 8 or 9 percent had invasive prostate cancer," Stamey says. "These guys in Detroit -- they were at least healthy enough to be in a fight. But what it really shows is that for every increasing decade, there's a straight line up as to how much cancer you find, so that 50 years later -- men in their seventies -- 80 percent have prostate cancer. What that really says is that this is a cancer that all of us get if we live long enough: It's a ubiquitous disease."
There's no sign that physicians have backed away from PSA testing. University of Virginia researchers who surveyed 176 primary-care physicians in 1993 and again in 1998 found that 81 percent of doctors in 1998 ordered PSA tests as part of routine checkups, an 8 percent increase from five years earlier. But fewer than half of the physicians in the second survey thought early detection and treatment would save lives. Rather, researchers reported, doctors ordered the tests because they believed PSA screens were a standard of care and because they feared malpractice suits if they didn't test patients who were subsequently diagnosed with prostate cancer.
One thing is certain: PSA testing has proven a bonanza for test manufacturers and urologists who perform biopsies using test results as a guide. A researcher at a major university who has published more than 200 articles in peer-reviewed medical journals says unreliable PSA tests have made big bucks for doctors.
"The average urologist in the United States in private practice does about ten biopsies a week," says the physician, who spoke on the condition that his name not be published. "Now, he gets $1,000 for a biopsy in a man. That biopsy takes ten minutes to do. That pays for everything in the office -- the nurse, the rental space, everything else. The rest is gravy, then: all of his surgery. But it's not just urologists. It's the companies that make PSA [tests] and advertise it and drive it. The cottage industry is so huge that I don't believe we can change the practice in this country until we have an honest-to-goodness marker, and that marker's got to be proportional to how much cancer a man has, since we all get it."