Similar CT lung screening positive rates and malignancy detection rates between group 2 and group 1 (NLST population) offer the potential to save thousands of additional lives every year by expanding CT lung screening eligibility to include group 2 high-risk individuals [13]. We found no statistically see more significant difference in the rate of positive results between NCCN group 2 and group 1 (NLST population), with overall positive results equivalent to those reported in the prevalence screen of the NLST. “
“The National Lung Screening Trial (NLST) demonstrated that CT lung screening reduces lung cancer–specific mortality in high-risk patients when the minimum

size of a positive pulmonary nodule is set at 4 mm [1]. Because more than half of baseline examinations in the NLST were positive for nodules 4 to 6 mm in size, raising the threshold for a positive result

to 6 mm would decrease the baseline NLST positive rate from 27.3% to approximately 13.4% [1]. Given the 0.5% positive predictive value (PPV) in the NLST of an examination positive for a nodule measuring 4 to 6 mm, increasing the threshold of positive CT lung screening results to 6 mm has the potential to increase the PPV by a factor of 1.8 (7.2% at 6 mm vs 3.8% at 4 mm) without significantly affecting the sensitivity to detect malignancy [1]. The International Early Lung Cancer Action Program reported an analogous observation: a reduction in baseline positive results to 10.2% at a 6-mm solid nodule threshold Olaparib solubility dmso ID-8 compared with 16% at a 5-mm threshold. Notably, the same number of lung cancers was detected within 12 months at both thresholds

[2]. After publication of these International Early Lung Cancer Action Program findings, both the National Comprehensive Cancer Network (NCCN) and the ACR adopted 6 mm as the minimum nodule-size threshold for positive CT lung screening results 3 and 4. To further decrease the frequency of false-positive CT lung screening results, ACR Lung-RADS™ version 1.0 set the size of a positive nonsolid (ground-glass) nodule to 2 cm and the duration of nodule stability required to meet criteria for benign behavior to 3 months, compared with 2 years in the NLST [4]. In this study, we retroactively applied the ACR Lung-RADS positive nodule-size thresholds to our clinical CT lung screening results. These had originally been interpreted using the NCCN Clinical Practice Guidelines in Oncology: Lung Cancer Screening (version 1.2012), which set positive nodule thresholds similar to those used in the NLST (4 mm solid, 5 mm nonsolid, benign at 2-year stability). Recasting the results was performed to evaluate the resulting frequency of positive findings, PPV, and number of false negatives under the new structured reporting system.