New Classification System For Low-dose CT Screening For Lung Cancer Interview with:
Paul F. Pinsky, PhD
Acting Chief Early Detection Research Group
National Cancer Institute
Bethesda, MD, 20892

Medical Research: What is the background for this study? What are the main findings?

Response: The National Lung Screening Trial (NLST) reported, in 2011, a 20% reduction in lung cancer mortality with low-dose CT screening. However, there was a high false positive rate, around 25% in the first two screening rounds, and somewhat lower in the final round. In order to reduce the high false positive rate, and also to standardize the reported system for low-dose CT screening, analogous to the use of BIRADS for mammography screening, the American College of Radiology (ACR) developed the Lung-RADS classification system. It was released in May, 2014. Although it was developed based on published summary data from several studies, including the NLST, it was never applied to a large group of screened subjects on an individual basis. Therefore, we retrospectively applied Lung-RADS to previously collected, detailed screening data from the National Lung Screening Trial .

The major findings were that the false positive rate decreased very substantially using Lung-RADS instead of the original National Lung Screening Trial criteria. At the baseline screen, it decreased by 50% and at subsequent screens it decreased by 75%. There was also, however, a modest decrease in the sensitivity rate, from 93% to 85% at baseline and from 93% to 79% at subsequent screens.

Medical Research: What should clinicians and patients take away from your report?

Response: For clinicians and patients, the take-away is that with low-dose CT screening using Lung-RADS, the false positive rate would be expected to be substantially lower than that seen in the National Lung Screening Trial . This is important because of several factors, including anxiety associated with a false positive test, the possibility of invasive procedures, with risk of complications, following a (false) positive screen, and cost and resource utilization issues. Also, the sensitivity of the test may be modestly lower, meaning more cancers may be missed. The effect of missing these extra cancers on the life-saving benefit of low-dose CT is unknown, though it would be expected to also be modest.

Medical Research: What recommendations do you have for future research as a result of this study?

Response: For the future, it is critical to have ongoing monitoring of large groups of persons undergoing low-dose CT screening, optimally using registries, to see if, when used prospectively in actual clinical practice, Lung-RADS can achieve the same low false positive rates seen in this study, where Lung-RADS was applied retrospectiively. Also, it will be important to see if the sensitivity rates observed in the current study are also observed in clinical practice.


Performance of Lung-RADS in the National Lung Screening Trial: A Retrospective Assessment ONLINE FIRST

 Ann Intern Med. Published online 10 February 2015 doi:10.7326/M14-2086 Interview with:, & Paul F. Pinsky, PhD MPH (2015). New Classification System For Low-dose CT Screening For Lung Cancer