CA19-9
Encyclopedia
CA19-9 is a tumor marker
that is used primarily in the management of pancreatic cancer
.
in 1981.
discourage the use of CA19-9 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 CA19-9 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.
In people with pancreatic masses, CA19-9 can be useful in distinguishing between cancer and other diseases of the gland.
, esophageal cancer
and hepatocellular carcinoma
. Apart from cancer, elevated levels may also occur in pancreatitis
, cirrhosis
, and diseases of the bile ducts. It can be elevated in people with obstruction of the bile duct
s.
In patients who lack the Lewis antigen (a blood type protein on red blood cell
s), which is about 10% of the Caucasian population, CA19-9 is not expressed, even in those with large tumors. This is because of a deficiency of a fucosyltransferase
enzyme that is needed to produce CA19-9 as well as the Lewis antigen.
Tumor marker
A tumor marker is a substance found in the blood, urine, or body tissues that can be elevated in cancer, among other tissue types. There are many different tumor markers, each indicative of a particular disease process, and they are used in oncology to help detect the presence of cancer...
that is used primarily in the management of pancreatic cancer
Pancreatic cancer
Pancreatic cancer refers to a malignant neoplasm of the pancreas. The most common type of pancreatic cancer, accounting for 95% of these tumors is adenocarcinoma, which arises within the exocrine component of the pancreas. A minority arises from the islet cells and is classified as a...
.
History
CA19-9 was discovered in patients with colon cancer and pancreatic cancerPancreatic cancer
Pancreatic cancer refers to a malignant neoplasm of the pancreas. The most common type of pancreatic cancer, accounting for 95% of these tumors is adenocarcinoma, which arises within the exocrine component of the pancreas. A minority arises from the islet cells and is classified as a...
in 1981.
Uses
Guidelines from the American Society of Clinical OncologyAmerican Society of Clinical Oncology
The American Society of Clinical Oncology is the world's leading professional organization representing physicians of all oncology subspecialties who care for people with cancer. Founded in 1964 by Drs...
discourage the use of CA19-9 as a screening test for cancer, particularly pancreatic cancer
Pancreatic cancer
Pancreatic cancer refers to a malignant neoplasm of the pancreas. The most common type of pancreatic cancer, accounting for 95% of these tumors is adenocarcinoma, which arises within the exocrine component of the pancreas. A minority arises from the islet cells and is classified as a...
. 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 CA19-9 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.
In people with pancreatic masses, CA19-9 can be useful in distinguishing between cancer and other diseases of the gland.
Limitations
CA19-9 can be elevated in many types of gastrointestinal cancer, such as colorectal cancerColorectal cancer
Colorectal cancer, commonly known as bowel cancer, is a cancer caused by uncontrolled cell growth , in the colon, rectum, or vermiform appendix. Colorectal cancer is clinically distinct from anal cancer, which affects the anus....
, esophageal cancer
Esophageal cancer
Esophageal cancer is malignancy of the esophagus. There are various subtypes, primarily squamous cell cancer and adenocarcinoma . Squamous cell cancer arises from the cells that line the upper part of the esophagus...
and hepatocellular carcinoma
Hepatocellular carcinoma
Hepatocellular carcinoma is the most common type of liver cancer. Most cases of HCC are secondary to either a viral hepatitide infection or cirrhosis .Compared to other cancers, HCC is quite a rare tumor in the United States...
. Apart from cancer, elevated levels may also occur in pancreatitis
Pancreatitis
Pancreatitis is inflammation of the pancreas. It occurs when pancreatic enzymes that digest food are activated in the pancreas instead of the small intestine. It may be acute – beginning suddenly and lasting a few days, or chronic – occurring over many years...
, cirrhosis
Cirrhosis
Cirrhosis is a consequence of chronic liver disease characterized by replacement of liver tissue by fibrosis, scar tissue and regenerative nodules , leading to loss of liver function...
, and diseases of the bile ducts. It can be elevated in people with obstruction of the bile duct
Bile duct
A bile duct is any of a number of long tube-like structures that carry bile.Bile, required for the digestion of food, is excreted by the liver into passages that carry bile toward the hepatic duct, which joins with the cystic duct to form the common bile duct, which opens into the intestine.The...
s.
In patients who lack the Lewis antigen (a blood type protein on red blood cell
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...
s), which is about 10% of the Caucasian population, CA19-9 is not expressed, even in those with large tumors. This is because of a deficiency of a fucosyltransferase
Fucosyltransferase
A fucosyltransferase is an enzyme that transfers an L-fucose sugar from a GDP-fucose donor substrate to an acceptor substrate...
enzyme that is needed to produce CA19-9 as well as the Lewis antigen.