Healthy Skepticism Library item: 2240

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Publication type: news

Kolata G.
Questions Grow Over Usefulness of Some Routine Cancer Tests
New York Times 2001 Dec 30
http://www.nytimes.com/2001/12/30/us/questions-grow-over-usefulness-of-some-routine-cancer-tests.html?pagewanted=1

Full text:

Medical researchers are increasingly questioning one of the most widely held beliefs in preventive medicine: that screening healthy people for cancer and catching it early saves lives.

The evidence shows that some screening tests are much more useful than others, said Dr. Barnett Kramer, the director of the Office of Medical Applications of Research at the National Institutes of Health.

Some, like Pap tests for cervical cancer and tests for colon cancer, show clear benefits. But evidence for others, like mammography and a blood test for early signs of prostate cancer, is less clear, researchers say, and some experts dispute whether their widespread use actually reduces death rates from cancer. And some new tests, like spiral CT scans of the lungs, are being marketed to patients before they have been shown in large, rigorous studies to benefit anyone.

Tests that detect cancer cannot always discern whether the cancer is one that will ultimately kill or is an indolent tumor that might never produce noticeable symptoms.

Even the critics of widespread testing are not necessarily advocating that people forgo it. But they say people should know what the demonstrated benefits are, and the risks, because once people know they have a cancer they usually seek treatment, and the treatments can be debilitating, even life-threatening.

“This is the `Emperor’s New Clothes’ of American medicine,” said Dr. Clifton K. Meador, director of the Meharry-Vanderbilt Alliance, a cooperative program between the two medical schools in Nashville. Dr. Meador, who has written on the drawbacks of screening tests, said the general enthusiasm for screening tests reminded him of what a medical resident once replied when asked to define a well person: “Someone who has not been completely worked up.”

Such concerns became an issue recently when scientists in Denmark reported that their analysis of mammography studies had found that the tests did not lower the overall death rate from breast cancer and that, as a group, women who had the tests ended up with more surgery, including mastectomies, more radiation and chemotherapy than women who were not screened. Their analysis is now being studied and debated, but, many medical experts said, at the very least it points out that even mammography may produce the same problems as other screening tests.

Mammographers are not convinced, and they stress the advantages of finding cancers early. “Early diagnosis translates for many – but not all – women into lower mortality,” said Dr. Edward Sickles, a professor of radiology at the University of California at San Francisco. And doubts cast on a test’s effectiveness do not mean that individual people will want to forgo them.

But some researchers studying the issue say they have been personally sobered by the unforeseen consequences that can arise when seemingly healthy people sign up for a screening test.

Dr. Stephen Swensen, for example, said he began a study of lung cancer screening three years ago, hoping to find that it could prevent deaths from lung cancer, the leading cause of cancer death for American men and women.

He screened 1,520 smokers and former smokers with spiral CT lung scans. As he expected, Dr. Swensen, the chairman of the radiology department at the Mayo Clinic, found lung cancers – 37 malignant tumors. But he also found more than 2,800 suspicious lung nodules, hard lumps of cells ranging in size from a grain of rice to a pea, that required further testing. Sometimes the testing included chest surgery, which itself carries a 4 percent risk of death.

He found nodules of unknown significance on people’s kidneys and adrenal glands. And he found aneurysms, bulging bubbles on blood vessels. In the end, Dr. Swensen said, more than 90 percent of the group had something suspicious on one or more of their scans.

Some ended up with surgery that may have saved their lives. But many, Dr. Swensen said, suffered needless operations and other medical procedures for something that may have been innocuous.

It is not even clear yet whether the early diagnosis of lung cancers helped, Dr. Swensen said. Some of the tumors might have been too slow growing to be dangerous and others might have already spread by the time he found them.

People who undergo spiral CT lung scans probably “assume that this could save their lives,” Dr. Swensen said. “That is absolutely, unequivocally unproven.”

But patients do not usually look at screening tests from that perspective. “They think they have little to lose,” said Dr. Steven H. Woolf, a professor of family practice at Virginia Commonwealth University in Fairfax and a member of the U.S. Preventative Services Task Force, a federally sponsored but independent group that evaluates evidence for screening tests and publishes guidelines. “They have little idea of the risk that awaits them.”

Others say the same.

“People think that the early detection of cancer is absolutely and unequivocally a good thing,” said Dr. Robert J. Stanley, the head of the radiology department at the University of Alabama at Birmingham. But even when a test detects cancer, the discovery may not be lifesaving.

For example, Dr. Stanley said, 60 percent to 100 percent of thyroid glands in people over 60 have cells in them that a pathologist would call cancer. But, he said, fewer than 1 percent of older people ever develop symptoms of thyroid cancer.

“I believe in screening,” said Dr. Andrew Wolf, associate professor of general internal medicine at the University of Virginia, who has studied what people understand about screening. “But I think physicians as well as the public tend to overblow the risks of cancer. And, more important, we overblow the risk reduction conferred by screening.”

Dr. Wolf said that he offered women Pap tests and, for those over 50, mammograms. He also offers colon cancer screening tests to men and women over 50. But he said: “I don’t get bent out of shape when people refuse. We can operate on the margins by offering these cancer screens, but let’s be honest about the expected impact.”

That may not be so easy, said Dr. William Black, a professor of radiology at Dartmouth-Hitchcock Medical Center in Lebanon, N.H. There are financial and legal incentives for doctors and medical centers to encourage screening tests, he said, and it can take time to sit down with patients and truly explain a test’s risks and benefits.

For example, Dr. Black said, health maintenance organizations are graded on the percentage of their members who get screenings like Pap tests and mammograms. And even when a test is controversial, like a prostate cancer test, doctors may hesitate to explain what is at stake.

That test, the P.S.A., for prostate specific antigen, can lead to the detection of tiny tumors. The problem, however, is that most prostate cancers grow very slowly, and men tend to die with them, not of them. Autopsy studies find that as many as 70 percent of men in their 80’s have early prostate cancers that were undetected during their lifetimes and caused no problems.

But doctors cannot tell which early cancers are dangerous and which are not – and 31,500 American men die of prostate cancer each year, making it the second leading cause of cancer deaths in men.

It may be, experts on prostate cancer say, that very aggressive cancers are unstoppable, whenever they are discovered, and others that grow slowly may not be dangerous. Yet once a tumor is found, doctors and their patients usually feel obliged to treat it, with radiation or surgery, which leaves many men incontinent and impotent.

Dr. Black tells of a doctor at a nearby medical center who took time to discuss the risks and benefits of the P.S.A. test on three separate office visits with one of his longtime patients. The man ended up not having the test. But shortly afterward he developed malignant prostate cancer and successfully sued the doctor. In July 1999, a jury awarded him $1.5 million, the largest jury award in the county superior court in a decade.

“It’s a whole lot easier to just go ahead and screen,” Dr. Black said.

Investigators say there are no ready answers on who should be tested, with what test and when. In an ideal world, they say, patients would consider the risks and benefits of each test and make an informed decision with the guidance of a wise doctor. But instead, they say, hurried doctors seldom spend much time discussing the tests and few patients ever question whether a test may do more harm than good. The result is that even tests whose benefits are accepted, like Pap tests for cancer of the cervix, are overused, with many women having it annually when once every three years would suffice.

But people bring their own values to bear when weighing evidence. For example, Donna Berry, a registered nurse who lives in Houston, said she started having mammograms when she was 45 – she is now 59 – even though she was well aware of a heated debate over whether they helped women in their 40’s. For Mrs. Berry, the test is worthwhile if there is the slightest chance that it might catch a cancer that can be cured.

In contrast, her husband, Donald Berry, who heads the biostatistics department at M. D. Anderson Cancer Center in Houston, is among the distinct minority of people who deliberately refuse screening tests for fear of the harm of overdiagnosis.

“I have this philosophy about looking for things,” Dr. Berry said. “I do go to the doctor if I am sick, but I don’t have routine checkups. I may live to regret it, but the evidence for most of these things does not exist.”