Additionally, we observed a significant increase in irisin expression in the group of patients with lymph node metastases (N1) (mean 1.86 ± 2.6 SD) in comparison with the group with mediastinal node metastases (N2) (mean 2.57 ± 2.8 SD; N1 vs. N2 p = 0.0200). Here, FNDC5 is linked to metastatic malignant neoplasm in the lymph nodes.