Cytokeratin 19, carcinoembryonic antigen, and epithelial cell adhesion molecule detect lung cancer lymph node metastasis in endobronchial ultrasound-guided transbronchial aspiration samples.

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.