June 30, 2011

CT Scans More Effective For Lung Cancer Screening

Scientists have found a 20 percent reduction in deaths from lung cancer among current or former heavy smokers who were screened with low-dose helical computer tomography (CT) versus those screened by chest X-ray.

The study establishes that low-dose helical CT is the first validated screening test that can reduce mortality due to lung cancer.

"Having a validated screening test that provides significant, but partial, protection against death from lung cancer complements "“ but should not be seen as replacing "“ ongoing efforts to control use of tobacco and to find other ways to prevent and treat lung cancer," Harold Varmus, M.D., director of the National Cancer Institute (NCI), who sponsored the study, said in a statement.

The National Lung Screening Trial (NLST) was a randomized national trial involving 53,454 current and former heavy smokers ages 55 to 74.  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. 

Participants in the study were randomly assigned to receive three annual screens with either low-dose helical CT or standard chest x-ray.  Helical X-rays obtain a multiple image scan on the entire chest, while standard chest X-rays produce just a single image of the whole chest.

The study found that 24.2 percent of the low-dose helical CT screens were positive and 6.9 percent of the chest X-rays were positive.  The majority of the positive screens led to additional tests.

Once a positive screen result was found, 96.4 percent of the low-dose helical CT tests and 94.5 percent of the chest x-ray exams were false positive.

Additional studies based on the complete NLST data are ongoing and will include reports on cost-effectiveness of low-dose helical CT as well as the ability to use the data to develop models that may help indicate whether other groups or smokers would benefit from screening with low-dose helical CT.

"These primary findings from the NLST provide a valuable insight into how to potentially decrease death due to lung cancer," NLST co-investigator, Christine Berg, M.D., of the NCI, said in a statement.  "But the most important method of decreasing lung cancer rates remains for smokers to quit smoking and for those who don't smoke to continue with their healthy behaviors."

The study was published online on Thursday in the New England Journal of Medicine.


Image Caption: This is a CT or CAT scan machine with spiral scanning capabilities. This particular model can produce 356-slice images. Credit: National Cancer Institute (NCI). Daniel Sone (Photographer)


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