NEW YORK—An evolving international protocol for early lung cancer screening is moving beyond initial scrutiny and pilot application, bringing prospects for widespread and cost-effective screening one step closer to clinical practice. Recommendations designed to reduce the frequency of diagnostic scans and radiation dose have been proposed and adopted by the International Early Lung Cancer Action Program (I-ELCAP), a collaborative global consortium of specialists who are gathering data and comparing notes on best practices in this field.
Researchers in I-ELCAP have been meeting twice a year to shape a shared set of principles to help guide future investigation. Participants in I-ELCAP, who met at the Fifth International Conference on Screening for Lung Cancer, specified that low-dose imaging be used for all diagnostic scans, except for high-resolution images that target identified nodules.
"Each conference becomes more focused," said Claudia I. Henschke, MD, PhD, chief of the Division of Chest Imaging, Weill Medical College of Cornell University. "Two years ago, we talked about study designs. Now, we are getting into findings and how to manage those findings. We are becoming much more specific to things that relate to CT screening, rather than generalities."
The preferred method for baseline and repeat screenings is multislice helical CT. As stated in the I-ELCAP protocol, multi-slice scanners provide higher resolution images, simplifying subsequent diagnostic workup.
Image readers primarily look for focal nonlinear opacities that do not meet the usual criteria for benign nodules. A baseline scan is positive if one to six noncalcified nodules are found. On repeat scans, readers look for growth of these "nodules of record."
Exactly when to do that repeat scan has been one subject of discussion. The I-ELCAP protocol had stated that high-resolution CT should be performed 6 months after baseline screening.
The recommendation emerging from this meeting is that patients with nodules 3 mm or less in diameter on initial screening CT be followed up not at 6 months, but at 1 year, avoiding a considerable number of unnecessary CT scans.
