Tumor marker Guidelines from the American Society of Clinical Oncology discourage the use of<unk>  as a screening test for cancer, particularly pancreatic cancer. The reason is that the test may be falsely normal (false negative) in many cases, or abnormally elevated in people who have no cancer at all (false positive). The main use of<unk>  is therefore to see whether a pancreatic tumor is secreting it; if that is the case, then the levels should fall when the tumor is treated, and they may rise again if the disease recurs. Therefore it is useful as a surrogate marker for relapse. In people with pancreatic masses,<unk>  can be useful in distinguishing between cancer and other diseases of the gland. Limitations<unk>  can be elevated in many types of gastrointestinal cancer, such as colorectal cancer, esophageal cancer and hepatocellular carcinoma. Apart from cancer, elevated levels may occur in pancreatitis, cirrhosis, and diseases of the bile ducts. It can also be elevated in people with obstruction of the bile ducts. In patients who lack the Lewis antigen A (a blood type antigen on red blood cells), which is about 10% of the Caucasian population,<unk>  is not produced by any cells, even in those with large tumors. This is because of a deficiency of a fucosyltransferase enzyme that is needed to produce Lewis antigen A.
CA19-9
CA 15-3
CA-125
AFP-L3
Alpha-fetoprotein
HER2/neu
Carcinoembryonic antigen peptide-1
BerEp4