Thorough workup algorithm is essential for lung screening trials

CHICAGO—The lack of an effective, detailed workup algorithm for positive results in multicenter lung cancer screening trials leads to a lower cancer yield from invasive procedures and later diagnoses for participants, according to a new study presented at the 2007 RSNA meeting.

During a scientific session, David Yankelevitz, MD, investigator in the New York Early Lung Cancer Action Program (NY-ELCAP), compared workup algorithms and results for the New York trial and the Lung Screening Study (LSS), the pilot study of the ongoing NCI-sponsored National Lung Screening Trial.

In NY-ELCAP, with 6,295 participants at risk for lung cancer, a very detailed algorithm was used following diagnosis with low-dose spiral CT. In contrast, the LSS, which randomized patients to spiral CT or chest x-ray, did not specify an algorithm, as organizers determined that they could not dictate medical practice. Dr. Yankelevitz's study analyzed results for 1,586 participants in the LSS's CT arm.

Participants in the two studies were at similar risk for lung cancer, had the same initial baseline test, and had an annual repeat test.

In the NY-ELCAP, 92% of invasive procedures performed after baseline screening resulted in cancer detection and 92% were also positive when performed as a result of the annual repeat CT exam.

By comparison, in LSS participants, 57% of invasive procedures turned up cancer on baseline screening and 44% on the annual repeat exam.

At baseline in both studies, cancers were detected at larger sizes, as expected. However, the size of cancer detected at annual repeat differed markedly, as 55% were smaller than 10 mm in the NY-ELCAP study, whereas only 13% were smaller than 10 mm for LSS.

The researchers also noted that the percent of cancers detected at stage I was higher in the New York study relative to the LSS.

Patient outcomes were better in the NY-ELCAP study, most likely due to differences in the workup algorithms, according to Dr. Yankelevitz, professor of radiology at Weill Cornell Medical College.

"This study shows the benefit of workup algorithms in screening protocols. Screening is not just about the initial test; it includes the baseline screening test all the way thorough diagnostics, including pathology," he said in an interview after the RSNA session.