Although the CEACAM5 glycoprotein has been extensively studied and validated in the management of various gastrointestinal malignant neoplasms, the same cannot be said in lung cancer.21,25 Literature reports17,18,23,27,28 demonstrate variable expression of the glycoprotein in lung cancer, and significant geographic variables are associated with the data. This evidence concerns the gene CEACAM5 and digestive system cancer.