CXCL8 and chronic obstructive pulmonary disease: In the two COPD patients (out of 39), who were incidentally diagnosed with lung cancer metastasis, the levels of these serum biomarkers were determined [VEGF (2658.0, 1013.5 pg/ml), IL-8 (11.8, 23.7 pg/ml), MMP-9 (661.8, 1166.7 ng/ml) and MMP-2 (209.2, 95.7 ng/ml)].