Outcomes of Positive and Suspicious Findings in Clinical CT Lung Cancer Screening and the Road Ahead.

RATIONALE Future optimization of CT lung cancer screening algorithms will depend on clinical outcomes data. OBJECTIVES To report the outcomes of positive and suspicious findings in a clinical CT lung cancer screening program. METHODS We retrospectively reviewed results for patients from our institution undergoing lung cancer screening from 1/2012 through 12/2018, with follow-up through 12/2019. All exams were retrospectively re-scored using Lung-RADS® v1.1. Metrics assessed included positive, probably benign and suspicious exam rates, frequency/nature of care escalation, and lung cancer detection rates following a positive, probably benign, and suspicious exam result and overall. We calculated time required to resolve suspicious exams as malignant or benign. Results were broken down by subcategories, reason for positive/suspicious designation, and screening round. RESULTS During the study period 4301 individuals underwent a total of 10897 exams. The number of positive (13.9%), suspicious (5.5%), and significant incidental (6.4%) findings were significantly higher at baseline screening. Cancer detection and false positive rates were 2.0% and 12.3% at baseline vs 1.3% and 5.1% across subsequent screening rounds respectively. Baseline solid nodule(s) 6 to < 8 mm were the only probably benign findings resulting in lung cancer detection within 12 months. New solid nodules 6 to < 8 mm were the only Lung-RADS® 4A findings falling within the Lung-RADS® predicted cancer detection range of 5-15% (12.8%). 38.5% of Lung-RADS® 4A cancers were detected within three months. CONCLUSIONS Modification of the definition and suggested workup of positive and suspicious lung cancer screening findings appears warranted.