Lung Cancer Screening Protocol Moves Forward

February 1, 2002

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.

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.

"The vast majority of these lesions are not cancers," said John Austin, MD, director of the Division of Thoracic Imaging, Columbia University. "Our current best guess is that under 3 mm, it’s good medical judgment to get a good low-dose screening 1 year later."

Participants also recommended that subjects who have nonsolid nodules greater than 5 mm in diameter on initial screening should be candidates for antibiotics and an early follow-up screening.

Researchers are also looking for bio-markers that might improve the sensitivity of spiral CT. There are still no available and validated biomarkers for early detection; however, there are several candidates under investigation, said Luis Montuenga, PhD, professor of cell biology, University of Navarra, Pamplona, Spain.

"The good thing about I-ELCAP is that we will have large populations of patients that have been analyzed for lung cancer with spiral CT," Dr. Montuenga said. "The correlation between this technique and biomarkers may give us lots of information."

Also notable at this meeting was a greater recognition among participants that screening programs must address psychological and behavioral issues to attenuate "cancer worry" and enhance retention of high-risk individuals.

The screening programs must also incorporate smoking cessation advice, something that was perhaps not emphasized as much in past meetings of the I-ELCAP group.

"The pulmonologist, with behavioral science specialists like psychiatrists, are probably the best suited to do this," Javier J. Zulueta, MD, PhD, director of the pulmonary service, University of Navarra. "We are the ones who are dealing with the patients, and probably the ones who are going to be the gateway to the different screening tests. I think we should get more involved in smoking cessation."

There is some evidence that showing a patient the results of a pulmonary function test might be a stimulus for the patient to consider quitting smoking. Furthermore, patients with some degree of emphysema might be more likely to consider quitting if they see their CT scan image than if they simply receive general medical advice. "These are the kinds of questions we need to ask in addition to researching biomarkers and chemoprevention," Dr. Zulueta said.