Cytokeratin 19, Carcinoembryonic Antigen, and Epithelial Cell Adhesion Molecule Detect Lung Cancer Lymph Node Metastasis in Endobronchial Ultrasound-Guided Transbronchial Aspiration Samples

Abstract Introduction Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) holds promise for accurate examination of mediastinal lymph nodes in NSCLC patients. However, it is not always possible to achieve a definitive diagnosis or subtype all cases. We aimed to evaluate the role of EBUS-TBNA combined with quantitative reverse transcription polymerase chain reaction (qRT-PCR) and flow cytometry (FCM) to assess tumor-associated antigens and immune responses to identify metastases and pathological patterns in lymph node aspirates. Patients and Methods EBUS-TBNA samples from patients with NSCLC (n = 33) and nonmalignant diseases (n = 17) were prospectively collected. Cytokeratin 19 (CK-19), carcinoembryonic antigen (CEA), epithelial cell adhesion molecule (EPCAM), sialyl-Lewis x , CD44, and the immune compartment were analyzed using qRT-PCR and FCM. Results In the NSCLC patients, the epithelial cell compartment was significantly increased (30.8% vs. 12% CD45 − CK-19 + cells) and showed brighter CK-19 staining than controls ( P  = .039) using FCM. Carcinoembryonic antigen was exclusively expressed by the NSCLC epithelial compartment (35% of the cases) and absent in controls. The NSCLC immune compartment showed an increased monocyte population ( P  = .04), and decreased lymphocyte subpopulations, anticipating a disruption in the distribution of myeloid and lymphoid immune cells. Quantitative reverse transcription polymerase chain reaction showed that CK-19 , CEA , and EPCAM transcripts were significantly higher in NSCLC. A positive correlation between the primary tumor lesion size and EPCAM (ρ = 0.476; P  = .005), CK-19 (ρ = 0.594; P  = .001), and CEA (ρ = 0.394; P  = .023) was also found. Conclusion The identification of CK-19, CEA, and EPCAM in EBUS-TBNA samples using FCM and qRT-PCR is feasible and might further aid in the detection of NSCLC lymph node metastasis.