IL6 and chronic obstructive pulmonary disease: The aim of this study is: 1) to assess a panel of different markers (IL-6, IL-8, TNF-α, CRP, PCR, IgE, platelet, neutrophil, and lymphocyte numbers, NLR, PLR, MPV, A1AT, fibrinogen, cholesterol and bilirubin) in three groups of patients (COPD, patients with COPD and LC [LC + COPD] and LC without COPD), focusing on the comparison between COPD and LC + COPD patients and, 2) to select those markers associated with LC + COPD and to create a score to predict the risk of presenting LC based on selected clinical parameters.