The GSEA results showed that gene sets related to the groups of LC coexisting with COPD were mainly enriched in the pathways of cell cycle, P53 signalling pathway, DNA replication, pyrimidine metabolism, insulin signalling pathway, etc. (FDR < 0.25 and nominal P < 0.05; Table 2). This evidence concerns the gene TP53 and chronic obstructive pulmonary disease.