Screening current or former smokers with the imaging technique of 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 from lung cancer, according to a study in the March 7 issue of JAMA.
Lung cancer accounts for 25 percent of cancer deaths and 6 percent of all deaths in the United States. Screening with chest x-rays is not effective in reducing the risk of advanced lung cancer or death, according to background information in the article. There is hope that lung cancer screening with computed tomography (CT) will be more effective at reducing deaths from lung cancer because it is more sensitive for the detection of very small nodules.
Peter B. Bach, M.D., M.A.P.P., of Memorial Sloan-Kettering cancer center, New York, and colleagues examined the effect of CT screening on individuals by comparing the frequency of lung cancer detection, resection (surgical removal of part of the lung), advanced lung cancer cases, and deaths from lung cancer with what would have occurred in the absence of screening (using a prediction model). The study (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 follow-up for a median (midpoint) of 3.9 years. Participants received annual CT scans with comprehensive evaluation and treatment of detected nodules.
The researchers found that individuals screened with CT were three times more likely to be diagnosed with lung cancer (144 diagnosed cases vs. 44.5 expected cases), and 10 times more likely to undergo a lung cancer surgery (109 individuals with lung surgery vs. 10.9 expected cases). Computed tomography 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 write.
“Our findings 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 write.
(JAMA. 2007;297:953-961. Available pre-embargo to the media at www.jamamedia.org)
Editor's Note: Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.
EDITORIAL: CT SCREENING FOR LUNG CANCER — SPIRALING INTO CONFUSION
In an accompanying editorial, William C. Black, M.D., of the Dartmouth-Hitchcock Medical Center, Lebanon, N.H.; and John A. Baron, M.D., of Dartmouth Medical School, Hanover, N.H., comment on the study in this week’s JAMA on CT screening for lung cancer, in which the results differed significantly from the 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.”