Low-dose CT Screening Found to Reduce Lung Cancer Deaths in Large Study

A large National Cancer Institute (NCI)–sponsored study has shown for the first time that a screening method can reduce deaths from lung cancer by detecting cancers at relatively early stages.

 

The National Lung Screening Trial (NLST), a randomized national trial involving more than 53,000 current and former heavy smokers ages 55 to 74 years, compared the effects of two screening methods for lung cancer—low-dose helical computed tomography (CT) and standard chest radiography—on lung cancer mortality. Results showed a highly significant 20% reduction in lung cancer deaths among trial participants screened with low-dose helical CT.

 

“Lung cancer is the leading cause of cancer mortality in the United States and throughout the world, so a validated approach that can reduce lung cancer mortality by even 20% has the potential to spare very significant numbers of people from the ravages of this disease,” said NCI director Harold Varmus, MD.

 

Over a 20-month period starting in August 2002, the NLST enrolled more than 53,500 men and women at 33 trial sites nationwide. Participants were required to have a smoking history of at least 30 pack-years and were either current or former smokers without signs, symptoms, or history of lung cancer at enrollment.

 

Participants were randomly assigned to receive three annual screens with either low-dose helical CT (often referred to as spiral CT) or standard chest radiograph. Screening was done at enrollment and at the end of their first and second years on the trial, and participants were then followed for up to another 5 years.

 

As of October 20, 2010, 354 participants in the CT arm of the study had died of lung cancer compared with 442 of those in the chest radiograph group. The Data and Safety Monitoring Board concluded that this 20.3% reduction in lung cancer mortality met the standard for statistical significance and recommended ending the study.

 

“This is the first time that we have seen clear evidence of a significant reduction in lung cancer mortality with a screening test in a randomized controlled trial. The fact that low-dose helical CT provides a decided benefit is a result that will have implications for the screening and management of lung cancer for many years to come,” said Christine Berg, MD, NLST project officer for the Lung Screening Study at NCI.

 

An ancillary finding was that all-cause mortality was 7% lower in participants screened with low-dose helical CT than in those screened with chest radiograph. Further analysis will be required to fully elucidate the reason for this difference.

 

The investigators do not recommend helical CT screening for all smokers, pointing out that it has several possible disadvantages, including the cumulative effects of radiation from multiple CT scans; false-positive results leading to further tests and procedures with possible complications, and costs and anxiety related to the screening process itself. They note too that the population enrolled in this study was a highly motivated and primarily urban group that was screened at major medical centers, and the results may not accurately predict the effects of recommending low-dose helical CT scanning for other populations.

 

Further information about the NLST can be found at http://www.cancer.gov/newscenter/qa/2002/nlstqaQA.