On the other hand, cytokeratin 19‐fragment (CYFRA21‐1) and carcinoembryonic antigen have been used as tumour markers in human lung adenocarcinoma (Dong et al., 2016; Zhao et al., 2014), and reports indicate that sensitivity increases when these markers are measured simultaneously with serum nectin‐4 (Takano et al., 2009). This evidence concerns the gene CEACAM5 and lung adenocarcinoma.