Positive Screens Are More Likely in a National Lung Cancer Screening Registry Than the National Lung Screening Trial.

Purpose: Although lung cancer screening (LCS) with low-dose chest CT (LDCT) is recommended for high-risk populations, little is known about how clinical screening compares with research trials. We compared Lung CT Screening Reporting and Data System (Lung-RADS) scores between a nationally screened population from the ACR's LCS Registry (LCSR) and the National Lung Screening Trial (NLST).

Methods: This retrospective study included baseline LDCT examinations from the LCSR and NLST. Patient characteristics (age, gender, smoking status, pack-years, and body mass index) were obtained. NLST LDCT results were recoded to Lung-RADS version 1.1. A multivariable multinomial logistic model was used to examine variations in Lung-RADS scores by screening group (LCSR versus NLST) and patient characteristics.

Results: In all, 686,011 and 26,432 participants from the LCSR and NLST, respectively, were included. Compared with the NLST, the LCSR population was older (mean age [SD]: 64.0 [5.4] versus 61.4 [5.0] years); P < .001) and included more female patients (47.9% versus 40.9%; P < .001), and its patients were more likely to be currently smoking (61.5% versus 48.1%; P < .001). After adjusting for age, gender, smoking history, and body mass index, the LCSR population was more significantly likely to have higher Lung-RADS scores than the NLST (adjusted odds ratio and 95% confidence interval > 1 for Lung-RADS scores 2, 3, 4A, 4B, 4X relative to Lung-RADS 1).

Conclusions: Lung-RADS scores in clinical LCS are higher than in the NLST, even after adjusting for known confounders such as age and smoking. This would imply higher rates of follow-up testing after LCS and potentially higher cancer rates in the clinically screened population than the NLST.