CURRENT AND FORMER HEAVY SMOKERS screened with low-dose spiral computed tomography (CT) scanning had a 20-percent greater reduction in deaths from lung cancer than those screened with conventional chest X-rays, according to the results of a decade-long clinical trial involving more than 53,000 people. Results of the National Lung Screening Trial (NLST) study were published in the New England Journal of Medicine.
“These findings confirm that low-dose CT screening can decrease deaths from lung cancer, which is expected to kill more than 150,000 Americans this year alone,” says Denise R. Aberle, M.D., an NLST principal investigator and vice chair for research in the UCLA Department of Radiological Sciences. “This study also will provide us with a roadmap for public-policy development in terms of lung-cancer screening in the years to come.”
Participants in the study were randomly assigned to receive three annual screenings with either the low-dose spiral CT or the standard chest X-ray. Spiral CT uses X-rays to obtain multiple “slices” through the entire chest cavity during a seven-to-15-second breathhold. A standard chest X-ray requires only a sub-second breath-hold but produces just a single image of the whole chest in which anatomic structures overlie one another, perhaps obscuring a potential malignancy.
The NLST is the first trial with sufficient numbers of participants using a randomized design to enable the comparison of mortality differences between spiral CT and chest X-rays, Dr. Aberle says. While the results are encouraging and should reshape screening guidelines in the future, the scientist says, CT screening is not an alternative to smoking cessation.
Additional studies based on the NLST data set are ongoing and will include reports on the cost-effectiveness of sprial CT and the effects of the screening process on smoking behaviors over time.
The NLST was designed to answer specific questions about the screenings in older heavy smokers and was conducted at sites with sophisticated medical resources and experts.
“The NLST cannot answer all of the important questions about screening that will be significant for implementation,” Dr. Aberle says. “However, the NLST data can be used to develop mathematical models to determine how long screening should be performed and how often. In addition, the data can be used to determine whether or not other groups at risk of lung cancer, such as light smokers, those with family histories of lung cancer or individuals with lung diseases like emphysema, would benefit from screening with spiral CT scanning.”