Introduction: Various subtypes of circulating cancer-associated cells in the blood are described. A unique circulating, large, and polymorphonuclear cell with a dual epithelial and myeloid phenotype has been suggested as a tumor-macrophage fusion cell (TMF). The goal of the study was to identify the impact of distinct TMFs on survival among patients with NSCLC.
Methods: In this prospective trial, 7.5 mL of whole blood sample was collected. After microfilter enrichment, immunofluorescent staining was performed, identifying TMFs as greater than or equal to 30 μm in size and dual epithelial (cytokeratin 8, 18, or 19-, or epithelial cell adhesion molecule-positive) and myeloid- or macrophage-positive (CD14- or CD45-positive) cells with at least one 4',6-diamidino-2-phenylindole+ nucleus.
Results: Circulating TMFs were identified in 88 of 115 patients (76.5%) with NSCLC (mean 3.052 [SEM ± 0.306]; median 2 [range 0-17]) but were rare in long-term smokers without cancer (6 of 87 [6.9%]; 0.081 [±0.034]; 0 [0-2]), and absent in 20 healthy controls. Comparing the presence of TMFs in patients with NSCLC versus smokers without cancer, specificity was 93.1% (95% confidence interval: 85.6-97.4%) and sensitivity 76.5% (95% confidence interval: 67.7%-83.9%). TMF counts correlated with American Joint Committee on Cancer tumor stages. More importantly, more than one TMF and giant TMFs sizes greater than or equal to 50 μm were associated with statistically significantly shorter overall and cancer-specific disease-free (p < 0.05) survival after curative resection for stage I to IIIA. Giant TMFs greater than or equal to 50 μm size were an independent survival predictor by multivariate analysis.
Conclusions: Circulating, in particular, giant TMFs are associated with aggressive clinical behavior in surgically treated patients with NSCLC. The biological role of unique TMFs will need to be further investigated, as these may have a potential impact on immune responses toward cancer.
Keywords: Circulating tumor cells; Fusion cells; Liquid biomarkers; Non–small cell lung cancer.
Published by Elsevier Inc.