CEA was first discovered in 1965 by Phil Gold and Samuel O, Freedman in intestinal cancer tissue extracts. CEA is a cancer embryonic antigen. It is mainly derived from the fetal gastrointestinal tract and blood. It is also present in small amounts in normal human intestinal, pancreatic and liver tissues. CEA synthesis is inhibited after birth and, therefore, the concentration of CEA in the blood of normal individuals is very low. Clinically, CEA measurement is mainly used for the treatment and follow-up of patients with colorectal cancer. Patients with gastric, pancreatic, lung, breast, and thyroid cancers can also have elevated blood CEA. However, elevated CEA is not seen only in patients with tumors. Ulcerative colitis, pancreatitis, cirrhosis, chronic obstructive pulmonary disease, Crohn’s disease, hypothyroidism, and smokers may all have increased CEA. In benign disease, CEA is usually mildly elevated. This means that an increased CEA could be a result of having a tumor, or it could be caused by other causes such as cirrhosis, colitis, or chronic obstructive pulmonary disease. Do not worry too much, but do not take it lightly, please go to oncology specialist for further treatment.