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19-9

Cancer-associated antigen

CA 19-9

CA 19-9 is a glycoprotein that appears on the surface of some cancer cells. It is mainly associated with pancreatic cancer but can also be elevated in other conditions such as bile duct cancer and colorectal cancer. It is produced by normal cells in the gastrointestinal tract but in higher concentrations by cancer cells.

Contents

Analysis of the tumor marker CA 19-9?

Analysis of CA 19-9 is used to help identify and monitor treatment of primarily pancreatic cancer. However, elevated levels of CA 19-9 can also be seen in other malignant and benign conditions, making it not a specific tumor marker for pancreatic cancer.

Cancer forms where CA 19-9 can occur in elevated concentrations:

  • Pancreatic cancer (70-90% of cases)
  • Bile duct cancer (up to 80% of cases)
  • Colorectal cancer (approx. 30-40% of cases)
  • Liver cancer
  • Stomach cancer (ventricular cancer)

Benign conditions where the CA 19-9 concentration may be elevated:

  • Liver cirrhosis
  • Pancreatitis (inflammation of the pancreas)
  • Cholecystitis (inflammation of the gallbladder)
  • Inflammatory bowel diseases (eg Crohn's disease)
  • Diabetes mellitus

CA 19-9 is therefore not a specific tumor marker, which means that elevated levels can occur in several different forms of cancer and also in non-malignant conditions. Therefore, the CA 19-9 assay should always be interpreted in conjunction with other clinical findings and other diagnostic tests. By measuring the concentration of CA 19-9 in the blood, the doctor can obtain important information that can be used as part of diagnostics and treatment.

  • Identify cancer risk: If a patient presents with symptoms such as abdominal pain, weight loss, or jaundice, a CA 19-9 test can help determine if further investigations are needed.
  • Follow the effect of treatment: During and after treatment for pancreatic cancer, CA 19-9 levels are measured regularly to see how well the treatment is working. A decrease in CA 19-9 levels often indicates that the treatment is effective.
  • Detect recurrence early: If CA 19-9 levels start to rise again after stopping treatment, this may be an early sign that the cancer has returned.

It is important to note that elevated CA 19-9 levels do not always mean that you have cancer. Levels may also be elevated in other conditions, including benign diseases. Therefore, the CA 19-9 test is most often used in conjunction with other examinations, such as imaging, to provide a more complete picture of the patient's state of health. The test is a valuable tool for doctors to make informed decisions about diagnosis and treatment.

Interpretation of test answers S-CA 19-9

Sample responses may vary by up to 10–20% due to sampling variation, method error and individual variations. Only changes of 20% or more are considered clinically significant, while smaller changes should be interpreted with caution and confirmed with repeated testing.

Elevated levels of CA 19-9 (test response above 37 kU/L) can be observed in several malignant conditions such as pancreatic cancer, bile duct cancer, stomach cancer and colorectal cancer. It is also important to note that a slight increase in CA 19-9 can occur in benign conditions such as cystic fibrosis, liver cirrhosis, primary biliary cirrhosis, cholecystitis, pancreatitis and rheumatoid arthritis.

It is worth mentioning that the ability to produce the CA 19-9 antigen is dependent on the patient expressing the Lewis blood group antigen. If the patient lacks this antigen, they will not be able to produce CA 19-9, even if a malignancy is present. Therefore, a careful clinical assessment and a holistic view of the patient's state of health is required to correctly interpret the results and determine whether further investigation is needed.

Reference interval for CA 19-9

  • Lower than 37 U/mL

This means that CA 19-9 values ​​below 37 U/mL are considered to be within the normal range. Values ​​above this may indicate the need for further investigation, but must always be interpreted in connection with clinical findings and possible symptoms.