An independent panel of U.S. public health officials is recommending that physicians no longer use a blood test to screen men for prostate cancer. The Congressionally-created advisory group, the U.S. Preventive Services Task Force, says the widely-used test does more harm than good.
Prostate cancer is the second most commonly diagnosed cancer among men in the U.S. Last year, more than 240,000 mostly older men in their 60s got the news. An estimated 33,000 died of the disease.
The prostate is a small, walnut-shaped organ that’s part of the male reproductive system, producing the fluid that carries sperm.
Since the 1990s, the so-called prostate specific antigen or PSA test has been a routine part of medical care for men aged 55 and older in the U.S. and other developed countries.
The PSA test measures levels of a protein in the blood that are elevated in the presence of prostate cancer. If cancer is found, it is treated aggressively, in nearly 90 percent of patients, with radiation, surgery or estrogen therapy designed to shrink the tumor.
But the PSA test has a high rate of false positives. So, men who turn out to have no cancer at all, or whose tumors are so small they pose no real health threat, often get unnecessary interventions such as uncomfortable and medically risky prostate tissue biopsies.
In 2008, the Preventive Services panel recommended against PSA testing in men over 75 years of age. In arriving at its new recommendation that the PSA test should be abandoned for men of any age, the panel reviewed data from two large studies that analyzed the test's purported life-saving benefits.
Based on the findings of the U.S. and European trials, it concluded that the risks of prostate screening far outweigh its benefits, according to Preventive Services task force chair Virginia Moyer:
“The best case scenario, best case scenario, says one man in a thousand screened will avoid a prostate cancer death within ten years. At the same time, out of that same thousand men, two or three will have a serious complication like a blood clot, or a heart attack or a stroke; forty will have very significant complications of treatment, including erectile dysfunction, urinary incontinence or both,” Moyer said.
And, according to Moyer, five in 1,000 men will die within a month of prostate cancer surgery.
But critics of the task force's recommendation contend that the studies on which it is based were seriously flawed. In particular, they say, faulty methodology casts doubt on the conclusion of a recent U.S. trial of more than 76,000 men that there was no difference in prostate cancer deaths between screened and unscreened men.
The panel also relied on a study in seven European countries that also found the PSA test saved few if any lives. But critics say a later analysis that corrected for flaws in the study's methodology concluded that PSA screening reduced the risk for dying of prostate cancer by as much as one third.
Dr. William Catalona is professor of urology at Northwestern University’s school of medicine in Illinois and director of the school’s clinical prostate cancer program. In Catalona’s view, the task force’s recommendation borders on irresponsible.
“It’s very unwise, it’s unfounded and it’s certainly unproven. I just think it’s a very, very poor recommendation,” Catalona said.
Catalona says the PSA test identifies about ten to fifteen percent of men at risk for developing prostate cancer. Many men with elevated levels of prostate specific antigen will have biopsies, a procedure Catalona likens to having dental work done with the pain-killer, Novocain.
“It’s uncomfortable. It hurts for a little while but then, within a few days, it’s gone. And you are glad you had it done because you know if you didn’t have it done and if that tooth was really in danger of developing an abscess, that it could have been much worse,” Catalona said.
Task force chair Virginia Moyer says the panel is not recommending the PSA test never be used, only that it should not be routinely offered.
“It doesn’t mean if a man desperately wants to be screened and he thoroughly understands the potential benefits and the known harms that he should not be permitted to do it. That really comes down to an individual choice. This is one of those extremely close calls,” Moyer said.
The U.S. Preventive Services Task Force recommendation on PSA screening is not binding on physicians, but it can influence medical insurance coverage of the procedure. The recommendation, and Dr. William Catalona's critical commentary, are published in the journal Annals of Internal Medicine.