Location and volume of screen-detected lung nodules: post hoc analysis from the UK Lung Cancer Screening (UKLS) trial

<bold>Introduction:</bold> UKLS trial showed that a single round of LDCT screening can reduce lung cancer deaths. However, nodule distribution regarding location and size remains a topic of interest, especially for the choice of workup of suspicious nodules. <bold>Objective:</bold> To analyze the location of nodules with a volume >100 mm³ in the UKLS trial, and to provide insights into their role in distinguishing between malignant and benign lesion in early lung cancer detection. <bold>Methods:</bold> 416 participants with 616 baseline lung nodules >100 mm³ were included. Nodule location was categorized by lobe and by attachment: intraparenchymal, juxta pleural or pleural-based. Nodules were classified based on semi-automated volume: 100 mm³–300 mm³ and >300 mm³. Nodules were classified as non-benign or benign based on radiologist interpretation. Chi-Square tests were used to demonstrate the association between nodule location and volume with radiologist interpretation. <bold>Results:</bold> Among 616 lung nodules, 160 (26%) were located in left lower lobe, 95 (15%) in left upper lobe (LUL), 158 (25.6%) in right lower lobe, and 128 (20.8%) in right upper lobe (RUL). Radiologists classified 401 nodules (65.1%) as non-benign and 215 (34.9%) as benign. Features predicting non-benign classification included intraparenchymal location (264/271 nodules, 97.4%, p<0.001), location in the LUL (74/95 nodules, 77.9%) and RUL (101/128 nodules, 78.9%, both p<0.001), and volume >300 mm³ (150/206 nodules, 72.8%, p=0.004). <bold>Conclusion:</bold> Nodules located intraparenchymally, in upper lobes and with volume >300mm3 are significantly associated with non-benign radiological classification.