GRP and small cell lung carcinoma: The specific reasons are as follows: ProGrp is a gastrointestinal hormone commonly found in various neuroendocrine-derived tumours, and clinical studies have found that it has high sensitivity and specificity for the diagnosis of small-cell lung cancer and can be used as a marker for small-cell lung cancer, which helps in the diagnosis and clinical treatment of small-cell lung cancer disease [12].CEA is an acidic glycoprotein in intestinal cancer, mainly in the embryonic stage by the small intestine and the liver.