NEW YORKAn 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
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.