PSA test for prostate cancer may confuse: Experts debate its continued use

By Dr. Ananya Mandal, MDOct 11 2011

According to new research the PSA test for prostate cancer does more harm than good. This week, the United States Preventive Services Task Force is expected to announce its recommendation against routine testing for blood levels of prostate-specific antigen, the protein that can be a signal of prostate cancer.

Its previous advice, in 2008, recommended against the PSA only for men 75 and older; most doctors agree that older men with undiagnosed prostate cancer are likely to die of something else.

According to the panel research shows that over all, the test does not save lives and leads to unnecessary surgery and radiation treatment for slow-growing cancers that would never have caused harm. As for faster-growing, invasive cancers, there’s no proof that P.S.A. tests and earlier treatment offer any overall benefit. There are however many who are convinced that the test saved their lives by helping their doctors detect cancer in its earliest stages.

Earlier some initial cases were advised watchful waiting. But doctors are divided about when to recommend watchful waiting. The decision can be guided by an indicator called the Gleason score, a measure of the aggressiveness of the cancer found in a biopsy, but there is often disagreement about how to care for men whose scores are in the middle — neither highly aggressive nor probably not aggressive. In addition, the biopsy process itself is imprecise; a standard “12-core biopsy” gives information about only one three-thousandth of the prostate, says Dr. Eric Klein of the Cleveland Clinic. According to research at Johns Hopkins, staging and grading mistakes occur in about 20 percent of specimens.

“You can’t be sure that even if you’ve found a cancer that is low-grade and seems innocuous that you haven’t missed a more aggressive cancer,” he said. “That’s the major limitation that leads to patient and family and physician uncertainty about who can be watched and who can’t be watched.”

PSA is a simple blood test, and it can pick up prostate cancer long before symptoms appear. However many of the cancers it detects are so slow-growing that they might never have caused problems. And their diagnosis via biopsy, and treatment, can be worse than the disease itself.

“I'm not saying that everybody should be screened, and there are real problems with PSA as a tool to find prostate cancer,” says Benjamin Davies, assistant professor of urology at the University of Pittsburgh. “But it does a disservice to Americans saying no one should be screened.”

Men rarely say they don't want a PSA, says urologist Elizabeth Kavaler of Lenox Hill Hospital in New York City. “The problem is that we wind up picking up a lot more cancer than we actually need to know about,” she says. What's needed, she adds, is a test to distinguish the relatively harmless cancers from the bad ones. For tiny, non-aggressive tumors, doctors increasingly advise “active surveillance,” giving patients periodic biopsies instead of treatment.

Dr. Deepak Kapoor, chairman and chief executive of Integrated Medical Professionals, which includes the nation's largest urology practice, disagreed saying, “We will not allow patients to die, which is what will happen if this recommendation is accepted.” “If we had a test that could distinguish between a cancer that was going to be aggressive and a cancer that was not, that would be fabulous,” task force chair Dr. Virginia Moyer of the Baylor College of Medicine, said.

“The U.S. Preventive Services Task Force is a group of primary care physicians like pediatricians and OB/GYNs who never treat prostate cancer,” said Dr. Herbert Lepor, professor of urology at New York University School of Medicine. “They have simply misinterpreted the studies and have not seen men die of this fatal disease.” About 1 in 6 U.S. men will be diagnosed with prostate cancer at some point in their life. In the U.S., about 217,000 men are diagnosed with prostate cancer each year, and 32,000 die.