After correction for multiple testing, NSCLC patients had a significant higher median level of thymus and activation regulated cytokine (TARC; C-C motif chemokine ligand 17 (CCL17)), Gro-b (C-X-C motif chemokine ligand 2 (CXCL2)), CXCL13, interleukin (IL)-6, IL-8 (CXCL8), platelet-derived growth factor subunit B (PDGF-BB), MMP-8 and MMP-12 in the serum compared with the COPD controls. Here, XCL2 is linked to chronic obstructive pulmonary disease.