Screening current or former smokers with computed tomography may increase the rate of diagnosis and treatment of lung cancer but may not necessarily reduce the risk of advanced lung cancer or death, according to an article in the March 7 issue of the Journal of the American Medical Association.

Peter B. Bach, MD, of Memorial Sloan-Kettering Cancer Center, New York, and colleagues used a prediction model to examine the effect of computed tomography (CT) screening on individuals by comparing the frequency of lung cancer detection, resection, advanced lung cancer cases, and deaths from lung cancer with the rates that would have occurred in the absence of screening. The current research (a combination of three studies) included 3,246 asymptomatic current or former smokers screened for lung cancer beginning in 1998 either at one of two academic medical centers in the United States or an academic medical center in Italy with median follow-up of 3.9 years. Participants received annual scans with comprehensive evaluation and treatment of detected nodules.

The researchers found that screened individuals were three times more likely to be diagnosed with lung cancer (144 diagnosed cases versus 44.5 expected cases), and 10 times more likely to undergo surgery (109 individuals with lung surgery versus 10.9 expected cases). However, screening did not appear to reduce the risk of advanced lung cancer diagnoses or deaths due to lung cancer.

"Our finding of a 10-fold increase in lung cancer surgeries resulting from screening underscores one of the potential public health consequences of CT screening. If the majority of excess early cancers found through screening are unlikely to progress rapidly to a point where they cause clinically significant disease or death, then the thoracic surgeries performed to remove them may be insufficiently beneficial to justify the resulting morbidities," the authors wrote.

"Our finding that CT screening is not associated with a reduction in the chance that a person will develop advanced lung cancer or die from lung cancer are important negative results that should influence how screening is viewed up until that time when more rigorous data are available from randomized trials."

"These findings, because they are thematically consistent with the findings of several randomized studies of lung cancer screening with chest X-ray, should raise doubts about the premise underpinning CT screening for lung cancer, and also raise concerns about its potential harms if pursued on a wide scale," the researchers concluded.

In an accompanying editorial, William C. Black, MD, and John A. Baron, MD, both of Dartmouth Medical School, Hanover, N.H., commented on the study, in which results differed significantly from results of a recent similar study.

"As Bach et al. acknowledge, formulation of screening policy should await the rigorous assessment that will be provided by ongoing randomized controlled trials (the National Lung Screening Trial in the U.S. and the NELSON Trial in Europe). Randomized controlled trials are the most reliable method for obtaining accurate assessments of the benefits and harms of screening in the underlying population. With this design, differences in outcome can be attributed to the intervention without reliance on highly modeled analyses with problematic assumptions. Although expensive and time-consuming, rigorous trials of cancer screening are far more cost-effective than what might be the alternative-widespread adoption of costly screening interventions that cause more harm than good."