A new study finds that nearly 40% of high-tech imaging scans conducted in the course of research reveal an unexpected abnormality that could be medically worrisome. These unsought discoveries -- known as "incidental findings" -- confront researchers with a dilemma: to tell or not to tell a research subject about a potential sign of illness found while a researcher was looking for something else?
And when researchers choose disclosure, research subjects must confront a dilemma as well: how much risk to accept -- and time, money and anxiety to expend -- to check out a finding that may or may not affect their long-term health?
The Archives of Internal Medicine, tracked the rate of incidental findings in 1,426 imaging scans undertaken for research at the Mayo Clinic in early 2004. An incidental finding is a red flag -- a solid mass, a lesion, a bulge in an artery or a tangle of nerves -- that is caught in the course of medical imaging studies, but was not the object of research or interest. The authors not only found that researchers happen upon such ambiguous signs of trouble frequently; they discovered that they do so most frequently in two situations: when research participants are older, and and when the imaging technology used is a computed tomography, or CT, scan focused on the abdominal/pelvic area or on the chest.
Those findings underscore growing concern among physicians over the widening use of advanced imaging techniques for diagnosis and "early detection" of diseases, including cancer: refinements in medical imaging have given health professionals ever-clearer ways to peer into the body and discern what appear to be the earliest stages of disease. But in so doing, those scans may often uncover signs of disease that would, in time, be vanquished by the body's immune system, sputter to a halt on its own, or progress so slowly it would not become evident in a patient's lifetime.
Whether those signs of incipient disease are found accidentally or by a physician looking for trouble, these discoveries generally prompt a flurry of further tests and treatment -- costly, risky and anxiety-inducing steps that may be of little benefit.
The study does suggest that the unsought findings caught on imaging studies are overwhelmingly -- though not always -- benign. Of 1,055 potentially significant abnormalities found in the course of research scans, only 35 were followed by actions to explore and/or treat the suspicious finding. Those resulted in a host of follow-up tests and, in some cases, treatment. For six lucky patients, the findings -- and the tests that followed -- brought clear medical benefit, the authors found. For two, the unintended findings ushered in a series of explorations that imposed a clear burden without any compensating benefit. And in 24 cases, the authors concluded it was a tossup whether the subject experienced more benefit or more harm from the finding.
"Although [incidental findings] may offer the possibility of substantial personal benefit to the participant, more commonly they are false-positive findings that lead to a cascade of further testing that presents additional risks and burdens," wrote Dr. Bernard Lo of the University of California San Francisco's program in medical ethics in an editorial that accompanied the Archives study.
For medical researchers, the high rate of incidental findings adds complexity both ethical and practical to their task. Current research guidelines and practices vary, meaning that while some researchers feel an obligation to disclose to a subject that scans have picked up "something," others do not. Lo wrote that future researchers using imaging scans in their trials should inform subjects that "incidental findings" are common and should have policies in place at the start of a trial for disclosure if a subject has said she wants to know of any such findings.
Physicians recommending scans for patients should also dispense better information about the pros and cons of such procedures, said Dr. Barnett S. Kramer, director of the National Institutes of Health's Office of Medical Applications of Research. Just as physicians are expected to inform a patients of the potential risks of taking a prescription drug or other treatment, they review the potential risks of diagnostic imaging tests -- including the high likelihood that they will find something unexpected, said Dr. Kramer.
The bottom line, says medical ethicist Dr. Howard Brody of the University of Texas' Medical Campus, Galveston: "We do far too many imaging studies, and many of them end up harming patients more than benefiting them."
Patients "would be well served by doctors who become more selective and conservative about ordering imaging studies," added Brody, who directs the Institute for Medical Humanities at UT. "If you run into such a doctor, she's not 'rationing care' or serving on some government 'death panel'; she's trying to preserve your health," he says.
-- Melissa Healy / Los Angeles Times
Things researchers find when looking for other things: What should they tell the test subject?
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