*Smoking status was not known in two cases. Quantitative results are presented as median (interquartile range). P < 0.05 was considered statistically significant. proGRP - progastrin-releasing peptide. CRP - C-reactive protein. NSE - neuron specific enolase. CEA - carcinoembryonic antigen. CYFRA - cytokeratin 19 fragment 21-1. COPD-E - exacerbation of COPD. COPD-R - remission of COPD. ADC - adenocarcinoma. SQCC - squamous cell carcinoma. NET - neuroendocrine tumor. Here, CEACAM5 is linked to squamous cell carcinoma.