Initial results from a large study have shown there to be 20% fewer deaths from lung cancer among people screened with low-dose helical computed tomography (CT) compared with standard chest x-ray, prompting investigators to stop the trial.

The National Lung Screening Trial enrolled 53,500 current or former smokers (at least 30 pack-years, as calculated by multiplying the average number of packs of cigarettes smoked per day by the number of years a person has smoked). The participants had no signs, symptoms, or history of lung cancer—the current leading cause of cancer mortality in the United States. They were randomized to three annual screens with either the low-dose helical CT (often referred to as spiral CT) or the x-ray.

By October 2010, 354 lung-cancer deaths had occurred in the CT group, compared with 442 in the x-ray arm. This 20.3% reduction represents the first clear evidence of a significant decrease in lung-cancer mortality with a screening test in a randomized controlled trial. The difference was statistically significant enough to end the study. The findings were published online ahead of print in the journal Radiology.

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