The National Lung Screening Trial (NLST) compared two ways of detecting lung cancer: low-dose helical computed tomography (CT) and standard chest X-ray. Both chest X-rays and low-dose helical CT scans have been used to find lung cancer early, but the effects of these screening techniques on lung cancer mortality rates had not been determined. NLST enrolled 53,454 current or former heavy smokers from 33 sites and coordinating centers across the United States.

In November 2010, the initial findings from the NLST were released.  On June 29, 2011, the primary results were published online in the New England Journal of Medicine and appeared in the print  issue on August 4, 2011.   These findings reveal that participants who received low-dose helical CT scans had a 20.0 percent lower risk of dying from lung cancer than participants who received standard chest X-rays.

The NCI press release and Q&A related to these published results provide a fuller explanation of the findings.