Do-It-Yourself Diagnosis
A CT scan can send a powerful message. So what's wrong with this picture?
Scan-happy. Rush North Shore still offers lung scans, but radiology chairman Leonard Berlin no longer promotes them. He has come to feel increasingly squeamish about scanning symptomless individuals. "Everybody has lung scars, and it's very difficult to differentiate them from little tiny nodules," he says.
Lung scans, it seems, are overly sensitive; they catch almost everything, no matter how small. And they aren't very specific. This combination produces a very high rate of "false positives"--findings that look like something but aren't. In the March issue of Radiology, an ongoing Mayo Clinic study reported that after two years, CT lung scans had identified suspect nodules in 1,049 out of 1,520 current or recent smokers. There were 2,832 nodules in all--nearly three per person.
How many mattered? The scans turned up 36 cancerous nodules. The other 2,796 were determined to be benign, a 98.7 percent rate of false positives. Eight individuals had to have surgery to remove nodules that then proved benign. "My profession is chest radiology, so I see all these people dying of lung cancer," says Stephen Swensen, the lead study author and radiology chair at the Mayo Clinic. "It's like a 747 full of people diving into a mountain every day. It drives me crazy. That's why I started looking into the possibility that scanning might save lives."
So far, Swensen believes, "there's no conclusive evidence that screening for lung cancer saves lives, and it could be doing more harm than good" when complications and deaths from unnecessary procedures are factored in. Leonard Berlin calls it the "cascade of testing"--one scan leading to another, followed by increasingly invasive procedures.
William Casarella, radiology chair of Emory University Hospital in Atlanta, is familiar with the phenomenon. Casarella, 65, is faithful about having a colonoscopy because of a family history of colon cancer. For his exam in November 2001, he opted for a virtual colonoscopy instead of the usual kind, in which a long tube, or endoscope, is snaked through the colon to examine the inner surface and snip suspicious growths for biopsy. He finds that it hurts--but knows that's because he declines sedation so he can get back to work quickly. "That's not very smart, I guess," he admits.
Mixed results. The colon scan was negative. But it also displayed a growth on Casarella's kidney, another on his liver, and several in his lungs. With dye pumped through his system for better contrast, a second scan showed that the one on the kidney was a harmless cyst but the liver growth wasn't. Tissue drawn from the liver didn't settle the issue. Neither did a PET (positron emission tomography) scan. A third CT scan, of the lungs, verified numerous nodules. Because the mass on the liver might indicate cancer that had spread to the lungs, three chunks of tissue were removed from the right lung.
"It was far more painful than I thought it would be," says Casarella. "It was good to go through it. Physicians talk about lung biopsies in a casual way because we don't have a good idea how painful and debilitating it is." Casarella was hospitalized for four days and needed narcotics for pain relief for two more weeks. It was five weeks before he felt normal. The final bill, completely paid by insurance, was $46,000. All the findings were negative.
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