Screening heavy smokers for lung cancer with a form of computed tomography (CT) reduced deaths by 20% compared with screening using x-ray techniques. But the experts who reported the findings say more information about the costs and the benefits of CT scans is needed before recommendations for lung cancer screening can be made.
The study, released online today in the New England Journal of Medicine, included 53 454 adults who had a history of cigarette smoking and were at high risk for lung cancer. They were enrolled in the National Lung Screening Trial, a study designed to determine whether deaths from lung cancer were lower among high-risk adults screened with CT scans compared with x-ray techniques.
Half of the enrollees were assigned to be screened with an x-ray technique known as chest radiography. The others were screened with low-dose helical CT, which can produce multiple cross-sectional images of internal organs. All were screened annually for 3 years and followed up for 3½ years with no additional screening.
In the CT group, 24.2% of participants had positive screening test results compared with 6.9% in the radiography group. But the majority of these were false-positive results that showed normal lymph nodes or benign inflamed tissue. False-positive results are an important, cautionary aspect of screening for any disease because they can result in unnecessary additional tests or treatment that could cause adverse events.
By the end of clinical evaluations, 356 participants in the CT group and 443 in the radiography group had died of lung cancer. The figures represent 20% fewer deaths from lung cancer in the CT group.
“Before public policy recommendations are crafted, the cost-effectiveness of low-dose CT screening must be rigorously analyzed,” the authors wrote. “The reduction in lung-cancer mortality must be weighed against the harms from positive screening results and overdiagnosis, as well as the costs.”