MDCT volume measurement as a diagnostic tool in lung cancer screening


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Matthijs Oudkerk
BCN / University of Groningen, The Netherlands

Abstract

In December 2003, the Dutch-Belgian NELSON trial, a Dutch acronym for "Nederlands-Leuvens Longkanker Screenings ONderzoek", has been launched.
Primary objective of the NELSON trial is to investigate whether screening for lung cancer by 16-detector multi-slice CT with 16 mm x 0.75 mm collimation and 15 mm table feed per rotation (pitch=1.5) in year 1, 2 and 4 will lead to a decrease in lung cancer mortality in high-risk subjects of at least 25% compared to a control group which receives no screening. In this presentation, the screening regimen and the classification and management of the screen-detected nodules at baseline and incidence screening is presented. This is the first large lung cancer screening trial in which the nodule management protocol is based on volumetric nodule assessment and the presence or absence of growth.
Furthermore, the base line results will be presented of 7557 participants who underwent CT screening in years 1, 2, and 4. We used software to evaluate a noncalcified nodule according to its volume or volume-doubling time. Growth was defined as an increase in volume of at least 25% between two scans. The first-round screening test was considered to be negative if the volume of a nodule was less than 50 mm3, if it was 50 to 500 mm3 but had not grown by the time of the 3-month follow-up CT, or if, in the case of those that had grown, the volume-doubling time was 400 days or more. In the first and second rounds of screening, 2.6% and 1.8% of the participants, respectively, had a positive test result. In round one, the sensitivity of the screen was 94.6% (95% confidence interval [CI], 86.5 to 98.0) and the negative predictive value 99.9% (95% CI, 99.9 to 100.0). In the 7361 subjects with a negative screening result in round one, 20 lung cancers were detected after 2 years of follow-up. The interim conclusion is that the chances of finding lung cancer 1 and 2 years after a negative first-round test are neglectable.