One of the things holding back wider acceptance of low-dose CT screening for lung cancer has been the high false-positive rate—between 20 and 50 percent. But a study published online Friday in Cancer indicates that false positives don’t seem to bother those being screened. The lesson, apparently, is to emphasize the “informed” part of informed consent.
Ilana F. Gareen, PhD, lead author of the Cancer article, explained the findings of the study:
Most people anticipated that participants who were told they had a positive screen result would experience increased anxiety and reduced quality of life. However, we did not find this to be the case.
She and her colleagues surveyed participants in the landmark National Lung Screening Trial (NLST), which created a major buzz when its initial results were released in November 2010. The trial found that subjects who received low-dose helical CT scans had a 20 percent lower risk of dying from lung cancer than those who got standard chest X-rays. Both one month and six months after screening, the researchers found no increased anxiety or decreased quality of life among the study subjects who had received positive initial diagnoses for cancer that turned out to be false.
That’s a boost for CT lung screening, which in December received a Grade B U.S. Preventive Services Task Force recommendation for those 55 to 80 who have a history of heavy smoking. As for why the subjects handled false-positive results with such equanimity, the researchers speculated that it came down to information.
“We think that the staff at each of the NLST sites did a very good job of providing informed consent to our participants,” Dr. Gareen said. “In advance of any screening, participants were advised that 20 to 50 percent of those screened would receive false-positive results, and that the participants might require additional workup to confirm that they were cancer-free.”
Equally thorough advance information would seem to be indicated for all screening subjects.
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