In terms of CRC diagnosis, CEA has been proven to be a sensitive marker for the early diagnosis of colorectal cancer, and many studies have combined CEA with other markers to improve the specificity of tumour diagnosis, which indicates that glutamine might be used in combination with CEA in the diagnosis of tumours in the future, not only in prognostic prediction [22, 23]. The gene discussed is CEACAM5; the disease is colorectal carcinoma.