Purpose: Low-dose computed tomography (LDCT) screening of high-risk patients decreases lung cancer-related mortality. However, high false-positive rates associated with LDCT result in unnecessary interventions. To distinguish non-small-cell lung cancer (NSCLC) from benign nodules, in the present study, we integrated cellular liquid biomarkers in patients with suspicious lung nodules (lung cancer screening reporting and data system [Lung-RADS] 4)., Methods: Prospectively, 7.5 mL of blood was collected from 221 individuals (training set: 90 nonscreened NSCLC patients, 74 high-risk screening patients with no/benign nodules [Lung-RADS 1-3], and 20 never smokers; validation set: 37 patients with suspicious nodules [Lung-RADS 4]). Circulating tumor cells (CTCs), CTC clusters, and tumor-macrophage fusion (TMF) cells were identified by blinded analyses. Screening patients underwent a median of two LDCTs (range, 1-4) with a median surveillance time of 30 (range, 11-50) months., Results: In the validation set of 37 Lung-RADS 4 patients, all circulating cellular biomarker counts ( P < .005; Wilcoxon test) and positivity rates were significantly higher in 23 biopsy-proven NSCLC patients (CTCs: 23 of 23 [100%], CTC clusters: 6 of 23 [26.1%], and TMF cells: 15 of 23 [65.2%]) than in 14 patients with biopsy-proven benign nodules (6 of 14 [42.9%], 0 of 14 [0%], and 2 of 14 [14.3%]). On the basis of cutoff values from the training set, logistic regression with receiver operating characteristic and area under the curve analyses demonstrated that CTCs (sensitivity: 0.870, specificity: 1.0, and area under the curve: 0.989) and TMF cells (0.652; 0.880; 0.790) complement LDCT in diagnosing NSCLC in Lung-RADS 4 patients., Conclusion: Cellular liquid biomarkers have a potential to complement LDCT interpretation of suspicious Lung-RADS 4 nodules to distinguish NSCLC from benign lung nodules. A future prospective, large-scale, multicenter clinical trial should validate the role of cellular liquid biomarkers in improving diagnostic accuracy in high-risk patients with Lung-RADS 4 nodules., Competing Interests: Kevin F. Staveley-O'CarrollHonoraria: AstraZeneca Klaus PantelHonoraria: Agena Bioscience, Novartis, Roche, Medac, Impulze, Ipsen, Sanofi, Merck KGaA, MSD, Beiersdorf, Galderma, Hummingbird, Illumina, Hello Healthcare, Menarini Silicon Biosystems, Abcam, Atheneum, CureVac, DeciBio, Inflection Biosciences, Molecular Health, TacticsConsulting or Advisory Role: Sanofi, Agena Bioscience, Hummingbird Diagnostics, Menarini Silicon BiosystemsResearch Funding: Janssen Diagnostics, Cancer-ID (Inst)Patents, Royalties, Other Intellectual Property: Application No. WO2016 128125A1, application No. 17157020.3—1405, application No. 10004180.5, application No. 07825055.2, application No. 95108760.7Travel, Accommodations, Expenses: Agena Bioscience Guangfu LiPatents, Royalties, Other Intellectual Property: Ceramide nanoliposomes as a method and device for immunotherapy (Inst) Aadel A. ChaudhuriLeadership: Droplet BiosciencesStock and Other Ownership Interests: Geneoscopy, Droplet BiosciencesHonoraria: RocheConsulting or Advisory Role: Geneoscopy, Roche, Tempus, AstraZeneca/Daiichi SankyoPatents, Royalties, Other Intellectual Property: US Patent No. US8685727B2Travel, Accommodations, Expenses: Roche, Foundation MedicineOther Relationship: Roche Jussuf T. KaifiPatents, Royalties, Other Intellectual Property: Cancer Biomarker detectionNo other potential conflicts of interest were reported.