The test used to screen for prostate cancer, the PSA (prostate-specific antigen) test, is controversial among many physicians. But even advocates of PSA testing do not recommend it for men who might not live long enough to see a benefit from screening.

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The potential benefits of PSA testing are unclear, but experts agree that a man would probably have to live more than a decade to experience them. This is because the forms of prostate cancer that are detected by PSA testing late in life often progress slowly, as opposed to the more aggressive and often fatal forms of the disease that may occur earlier.

The potential harms of PSA testing, on the other hand, can occur immediately and are often substantial. These include additional testing, psychological distress, and side effects from treating a disease that might never have caused any harm.

For these reasons, most prostate cancer screening guidelines recommend against testing elderly men with limited life expectancy. But many men in their 70s and 80s are being screened anyway, and this has raised concerns among some physicians.

"This test can definitely cause more harm than benefit when used in an elderly population with multiple health conditions," says Dr. Louise Walter, a geriatrician and researcher at the San Francisco Veterans Affairs (VA) Medical Center and the University of California, San Francisco.

She led a recent survey of PSA testing in the VA medical system. Many physicians have been ordering PSA tests for men in their 70s and 80s, including some men in poor health, the researchers reported last November in the Journal of the American Medical Association (JAMA).

"I was surprised by how often very elderly men who have other severe diseases are getting prostate cancer screening," says Dr. Walter, who undertook the study after seeing some of her patients being harmed by PSA testing.

The test, she points out, measures blood levels of the PSA protein and is thought to be less informative in older men. Changes associated with aging such as a benign enlarged prostate can cause high PSA levels even when there is no prostate cancer.

And the benefits of testing remain unproven for all men, regardless of age or life expectancy. Two large randomized trials are investigating whether screening reduces prostate cancer deaths. Both have been ongoing for about 12 years and have yet to demonstrate a survival advantage for the men being screened.

Nonetheless, the prospect of having cancer based on the test is "very scary" to many men. "They may not realize that prostate cancer can range from an indolent disease that will never affect anyone to aggressive cancers that will kill them," says Dr. Walter. 

Some of her patients became so distracted by looking for a disease they did not have that they neglected the diseases they did have.

She gives the example of an 85-year-old patient with inoperable heart disease. As she was treating him, another doctor tested his PSA and found it to be elevated. The patient grew anxious and requested a biopsy.

The result came back, and the doctor told him he had low-grade prostate cancer, which progresses slowly and kills relatively few people. The doctor told him not to worry, but the man couldn't stop worrying.

He considered himself a cancer patient and flew to Mexico for an alternative treatment. Meanwhile, his heart condition worsened, and he died of a heart attack 6 months later.

"He spent those final months worrying about his cancer, which was the least of his problems," says Dr. Walter. "He should never have been screened."

Her study last year suggests that his case may not be unique. More than half of nearly 600,000 men over age 70 had PSA testing at VA facilities in 2003. None of the men had a history of prostate cancer, and healthy men were screened at about the same rates as those with other diseases.

"This study points out that we are not doing a great job in terms of selecting people for screening," says Dr. Howard Parnes, who studies prostate cancer prevention in NCI's Division of Cancer Prevention.

Physicians may not be taking the whole person's health picture into account when making this screening decision, he adds.

"It's not that old men shouldn't be screened, but we should be selective in screening because the benefits take a while but the harms are immediate," says Dr. Parnes.  

The reasons for the high screening rates among veterans are not clear, but very few men asked for the test. Most likely, the tests were done as part of routine blood work that might include, for instance, testing cholesterol levels.

An editorial in the same issue of JAMA noted that physicians order the tests because patients overestimate their chances of dying from prostate cancer, as well as the efficacy of cancer treatment.

Another reason is that physicians are often rewarded for treating patients and may be severely penalized for missing a cancer. 

"This dilemma is quite common in the current health care system and certainly requires urgent attention in the near future," wrote Dr. Peter Albertsen of the University of Connecticut Health Center in the JAMA editorial.

In the meantime, Dr. Walter hopes that more physicians will talk openly with their elderly patients about the potential harms of PSA testing. "This is really about not harming people by avoiding a procedure they don't need," she says.

By Edward R. Winstead