Lung cancer is the leading cause of cancer death in the United States. Yet unlike breast, prostate, and colon cancer, there is not currently a widely accepted screening protocol for lung cancer. Studies of chest radiography and sputum cytology conducted in the 1970s did not reveal a decrease in mortality that justified the expense and complications of widespread lung-cancer screening.22
However, interest in lung-cancer screening was reinvigorated in 1999 with a report by Henschke et al. on the Early Lung Cancer Action Project (ELCAP), which is studying the use of low-dose helical CT in 1,000 volunteers age 60 or greater with at least a 10 pack-year history of smoking.23 The authors have thus far concluded that "low-dose CT can greatly improve the likelihood of detection of small non-calcified nodules, and thus of lung cancer at an earlier and potentially more curable stage."
Despite the lack of long-term mortality data for these patients, the preliminary ELCAP results were so promising that they spawned an immediate call by some to launch widespread lung-cancer screening programs using low-dose CT without bothering with further controlled studies. Professional organizations such as the Society of Thoracic Radiology have taken a more cautious approach, saying that existing results are inconclusive with regards to the effect on mortality; they do not advocate CT screening for lung cancer until further controlled studies are performed.24
A major National Lung Cancer Screening Trial (NLST) is currently being sponsored by the National Cancer Institute to investigate the efficacy of CT lung cancer screening.
The latest generation of multislice CT scanners allows for the imaging of the entire lung during a patient breathhold with isotropic millimeter or even submillimeter resolution. This should improve the detectability of small, subtle lung nodules that could easily be blurred into the background if imaging were performed with thicker slices, as would be required on a single-slice scanner.
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