To screen or not?

For healthy people, some preventive tests are not only unnecessary, but may also be inaccurate and harmful, experts say

Medicine & Science

March 17, 2003|By Erika Niedowski | Erika Niedowski,SUN STAFF

Men come wanting prostate screening exams. Women come seeking bone density scans. Some patients arrive with a long list of preventive tests they've heard about and convinced themselves they need.

It's Dr. Steven H. Woolf's job to explain why all of them might not be necessary - and could in some cases be harmful.

When Woolf started out 13 years ago, the world of preventive screenings was much easier to navigate: The tests were either recommended or they weren't.

"Now we have an era where we understand there's no universal recommendation that applies to everyone, and people have to make personal choices based on risk profiles, family history, personal preference and so forth," said the family physician in Fairfax, Va., and professor of family practice at Virginia Commonwealth University. "This makes life more difficult for both the doctor and the patient."

The debate over whether healthy people should be screened for everything from abdominal aneurysms to cancer to heart disease has widened in recent years, as newer technologies and more tests have become available and as more research emerges on the benefits, harms and costs.

To health-conscious patients, the issue seems simple: If there's a test, why not get it?

But for physicians, the answer is increasingly ambiguous, because in some cases science is only beginning to catch up to clinical practice. In the past 18 months, even some tests that had become doctor's office standards - including mammograms and prostate-specific antigen tests - have come under serious scrutiny.

The benefits of screening for high cholesterol, colorectal cancer and cervical cancer are well documented. But whether to screen for other conditions isn't as clear because early detection doesn't always mean early enough detection and faulty diagnoses may turn out to be the rule rather than the exception, said Dr. Barnett Kramer, associate director for disease prevention at the National Institutes of Health.

Diagnostic screenings have long been available. One of the earliest tests, for tuberculosis, was devised more than 100 years ago by German physician Robert Koch. The first Pap smear, which screens for cervical cancer, is thought to have been performed on a guinea pig in 1916. Kramer thinks it was a doctor at the Johns Hopkins School of Medicine, Joseph Bloodgood, who first spoke out about the benefits of early diagnosis and early treatment of disease in the 1920s. He thought cancer rates could be drastically reduced simply by having patients undergo physicals.

"The earliest screening test, in his mind, was a good physical examination," Kramer said.

Now, during routine physicals, doctors may have patients undergo tests ranging from blood work to X-rays to electrocardiograms, in addition to recommending other tests to middle-age patients.

Since they were introduced more than 70 years ago, breast X-rays have been widely recommended for women age 40 or 50. But that long-accepted endorsement was shaken in November 2001, when Danish researchers concluded that the most commonly noted studies supporting mammograms were flawed and should be discarded, and that the exams do not detect fatal cancers early enough to reduce the risk of dying.

An independent but federally supported panel of experts that makes screening recommendations, the Preventive Services Task Force, now says the evidence is insufficient to recommend for or against prostate screenings. Some tumors caught may never cause problems because they are slow-growing, said Dr. Kenneth S. Fink, the task force's program director. And treatment, including surgery and radiation, could lead to health problems, such as incontinence or impotence.

Doctors are continuing to recommend mammograms and PSA tests until more evidence is in, though they talk with patients about the caveats. Many, like Don Dickason, a retired college admissions dean from Princeton, N.J., choose to be screened.

Dickason is at risk for prostate cancer - his father died from it - so he gets regular PSA tests. The 71-year-old was a self-described "healthy camper" before a cancerous polyp turned up during a routine colorectal screening nearly nine years ago. He believes the screening saved his life. "[The doctor] found it about as early as humanly possible," he said.

Dr. Stephen W. Havas, a professor of epidemiology and preventive medicine at the University of Maryland School of Medicine, said that screenings should be done only for serious or life-threatening conditions for which there is both agreed-upon treatment and evidence that shows early intervention makes a difference. The screening's cost also has to be relatively modest to make it acceptable to the general public.

"One of the things that patients can do with their doctors if their doctors recommend a particular test is say: `What is the evidence that this is going to do any good?'" explained Havas. "And if they can't come up with a complete argument, then why do it?"

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