March 07, 2007
Wednesday PM

When it comes to cancer, early detection is supposed to help save lives.

But with lung cancer, it may do more harm than good, according to a new study by the Mayo Clinic and several other centers.

The scientists found that routine checkups with high-tech computed tomography scans had no effect on the number of people dying of lung cancer, even though the devices were able to detect more tiny tumors.

At the same time, the CT scans picked up suspicious nodules that turned out to be harmless in nearly three out of every four people, and led to a tenfold increase in lung surgeries in the study group, said Dr. Stephen Swensen, a Mayo Clinic radiologist and a co-author of the study. The study followed more than 3,200 former or current smokers for almost four years.

The report, in Wednesday's Journal of the American Medical Association, is the latest in a series of contradictory findings about the usefulness of CT scans in fighting lung cancer.

Last October, another team of scientists reported just the opposite in the New England Journal of Medicine: that routine CT scans can prevent up to 80 percent of lung cancer deaths by detecting tumors early enough to be treated.

The new study concluded "these findings ... should raise doubts about the premise underpinning CT screening for lung cancer, and also raise concerns about its potential harms if pursued on a wide scale."

In medical circles, a debate has been raging for years over whether CT scans should be used routinely to check for lung cancer, which kills about 162,000 Americans a year - more than any other type of cancer.

Insurance companies generally won't pay for the routine scans. But increasingly, medical centers that own CT machines have been promoting them to smokers and ex-smokers who are willing to pay several hundreds dollars out of pocket.

Among other things, scientists believe that some small cancers may pose little or no threat to patients, possibly because they're so slow-growing.

Swensen, the study's co-author, admitted that the benefits of a screening test seem obvious at first. "If CT can find a cancer when it's the size of a grain of rice or even sesame seed instead of a golf ball ... then it must be a better tool," he said. And yet, he added, "that's not been shown to be true."

Years ago, chest X-rays were commonly used in annual checkups for lung cancer. But that tradition faded after studies by the Mayo Clinic and others raised similar concerns about the benefits.

The CT scans, which are far more sensitive than X-rays, can detect even tinier abnormalities in the lungs and elsewhere. Yet in the latest study, 98 percent of the suspicious spots in this study turned out to be false alarms, which required more diagnostic tests to rule out cancer, Swensen said.

In all, lung cancer was diagnosed in 144 people as a result of the CT scans in the study, about three times the number expected for this population, the researchers reported. The vast majority had the earliest-stage cancer, which is thought to be the most curable.

If the screening saved lives, the scientists said, they would have seen a drop in the number of people who went on to develop advanced cancer or die of lung cancer. But after nearly four years, the numbers were the same as, or higher than, those found in similar populations.

However, 10 times as many patients had surgery to remove part of their lungs, the study found. "We could be doing more harm than good," said Swensen, who noted that the surgery carries a 2 to 4 percent risk of death. "Forget the money, forget the radiation. You could actually kill more people than you save by screening and jumping into it," he said.

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