A novel cytokine profile associated with cancer metastasis to mediastinal and hilar lymph nodes identified using fine needle aspiration biopsy – A pilot study

Cancer metastasis to the lymph nodes is indicative of a poor prognosis. An endobronchial ultrasound-guided fine needle aspiration (EBUS-FNA) biopsy is increasingly being used to sample paratracheal lymph nodes for simultaneous cancer diagnosis and staging. In this prospective, single-center study, we collected dedicated EBUS-FNA biopsies from 27 patients with enlarged paratracheal and hilar lymph nodes. Cytokines were assayed using Bio-Plex Pro human cancer biomarker panels (34 cytokines), in a Bio-Rad 200 suspension array system. A mean cytokine value was taken from each subject with more than 1 lymph node station EBUS-FNA biopsies. Malignant and benign histologic diagnoses were established in 16 and 12 patients, respectively. An initial analysis using the Kruskal–Wallis test with Sidak correction for multiple comparisons, showed significant elevation of sVEGFR-1, IL-6, VEGF-A, Angiopoeintin-2, uPA, sHER-2/neu and PLGF in malignant lymph node samples compared to benign samples. The univariate logistic regression analyses revealed that 6 cytokines were significant predictors and 1 cytokine (PLGF) was marginally significant for discrimination between benign and malignant samples. The prediction power of these cytokines as biomarkers were very high according to the area under the ROC curve. Multiple logistic regression for subsets of the seven cytokine combined; provided an almost complete discrimination between benign and malignant samples (AUC = 0.989). For screening and diagnostic purposes, we presented the optimal discrimination cut-off for each cytokine: sVEGFR-1 (2124.5 pg/mL), IL-6 (40.2 pg/mL), VEGF-A (1060.1 pg/mL), Angiopoeintin-2 (913.7 pg/mL), uPA (248.1 pg/mL), sHER-2/neu (5010 pg/mL) and PLGF (93.4 pg/mL). For the very first time, a novel cytokine profile associated with cancer metastasis to the paratracheal lymph nodes were reported.