Generality
The Carbohydrate Antigen 19-9 ( CA 19-9 ) is a protein that is produced in excess by the cells of many forms of gastrointestinal tumors . Consequently, the dosage of this marker is used for the initial typing of the neoplasm, to monitor the course of the disease and to evaluate the therapeutic response.
What's this
CA 19-9 is the abbreviation used to identify a tumor marker, especially useful for monitoring the extent of pancreatic cancer, its evolution over time and the therapeutic response to the treatments undertaken.
Increases in CA 19-9 have also been reported during non-neoplastic liver disorders, including liver cirrhosis; in the latter case, the marker values seem to be correlated with the degree of fibrosis and the severity of the disease.
Why do you measure
The Antigen Carbohydrate 19-9 belongs to the category of so-called tumor "markers" (substances that can be found in increased quantities, in blood, urine or other body fluids, in the presence of certain neoplasms).
CA 19-9 is used, in particular, as a marker in the diagnosis and follow-up of gastrointestinal tumors . Usually, antigen is used for pancreatic cancer, but also for other types of neoplastic processes, such as the biliary tract, stomach and colorectal processes. In the latter case, the CA 19-9 dosage is associated with the analysis of another marker, CEA (carcinoembryonic antigen) .
The Antigen Carbohydrate 19-9 is considered reliable both for evaluating the extension of the tumor and for monitoring the post-operative course . However, it should be noted that pancreatic cancer patients do not always have an increase in CA-19-9 levels. Furthermore, this parameter can be high even in the presence of inflammation of the biliary tract or other diseases.
For this reason, when an abnormal value of CA-19-9 is detected, it is good to investigate further with the determination of the carcinoembryonic antigen (CEA), bilirubin, and / or liver panel, in the presence of symptoms suggestive of pancreas. These include: abdominal pain, nausea, jaundice and weight loss.
When is the exam prescribed?
CA 19-9 is not a sensitive enough specific marker to be considered a useful tool for cancer screening.
Antigen Carbohydrate 19-9 is mainly used for:
- Facilitate the differential diagnosis of pancreatic cancer compared to other non-cancerous conditions, such as pancreatitis;
- Check the patient's response to pancreatic cancer treatment;
- Monitor and reveal possible recurrences of neoplastic disease.
CA 19-9 can be used as a tumor marker only if the tumor tissue produces significant quantities.
Test limits
In addition to this low specificity, the usefulness of this marker for diagnostic purposes is limited by non-optimal sensitivity; in fact, there are individuals who, despite being suffering from pancreatic cancer, do not have high levels of CA 19-9.
Furthermore, this marker is detectable in the serum of patients presenting with the Lewis antigen, and does not increase in case of pancreatic islet tumors (which represent about 1.3% of the total number of pancreatic cancer cases).
Unfortunately, as far as the CA 19-9 is concerned, it is very different from the characteristics of the ideal tumor marker: its low specificity and not optimal sensitivity, therefore make it unsuitable for population-based screening.
In other words, the CA19-9 level cannot be used as an absolute marker of the presence or absence of a malignant pathology of the pancreas. Rather, the test results should be interpreted only in conjunction with other investigations and diagnostic tools of the disease.
Pancreatic Cancer Monitoring
However, CA 19-9 is very useful in monitoring patients with already diagnosed and / or treated pancreatic cancer ; the increase in the values of this tumor antigen after surgery is in fact a light turned on by a resumption of the disease.
For the same reason, during chemotherapy, the CA 19-9 dosage can provide useful information on the patient's response to treatment, and help establish the likelihood of surviving the disease: high values are generally associated with a failure to respond to treatment, while the finding of continuous increases is indicative of progression of the disease (unfortunately the chemotherapeutic drugs are generally ineffective, therefore the monitoring of the levels of CA 19-9 is useful above all in the post-intervention of removal of the diseased part of pancreas).
The increase in CA 19-9 may precede by several months (on average three) the instrumental confirmation of the recovery of the disease.
CA 19-9 levels are useful as a screening method for people suffering from sclerosing cholangitis for the early diagnosis of cholangiocarcinoma.
Normal values
CA 19-9 levels are measured in a venous blood sample taken from a vein in the forearm, just like any other traditional blood test.
The normal values of CA 19-9 are lower than 40 U / ml.
Rates above 100 U / ml are extremely indicative of pancreatic cancer.
CA 19-9 High - Causes
In about 70-95% of patients with advanced pancreatic cancer, high concentrations of CA 19-9 are found. High levels of this marker may also be present in other types of neoplasms (intestine, lungs, gall bladder etc.) and in pathologies such as gallstones, pancreatitis, cystic fibrosis and liver disease. In healthy individuals, low concentrations of CA 19-9 may be present.
tumors
In association with CEA (Carcinoembryonic Antigen), the CA 19-9 dosage can be helpful in the diagnosis and monitoring of other gastrointestinal malignancies, especially in the colorectal and biliary tract diseases.
The levels of CA 19-9 tend to increase in the presence of tumors of the gastrointestinal tract, even if to a lesser extent, and in a lower percentage of cases than in the case of pancreatic cancer.
High levels of CA 19-9 can be appreciated in about 1/3 of women with ovarian tumors, especially if they are mucinous (80% of cases), and more rarely in subjects with lung, breast or uterus.
Benign diseases
Even benign conditions such as acute and chronic pancreatitis, cirrhosis, hepatitis, biliary obstruction, jaundice and hyperbilirubinemia, or diseases affecting the colon or lungs, can determine high levels of CA19-9.
How to measure it
The CA 19-9 exam is a laboratory analysis that is performed on a blood sample taken from the patient's arm.
Preparation
For the analysis of CA 19-9, fasting of at least 8 hours is required, to prevent the food from interfering with the result.
Interpretation of Results
- High values of CA 19-9 are an indicator of the presence of pancreatic cancer. The onset of a relapse is likely when a patient already treated for this malignancy has an increase in CA 19-9 associated with that of the carcino-embryonic antigen (CEA).
- High concentrations can also be observed during chronic diseases, such as cirrhosis, pancreatitis, renal failure and hepatitis.
- This test, however, is not sensitive and specific enough to be used for pancreatic cancer screening, although values above 100 U / ml are extremely indicative of the disease.
