Synonyms

   Cancer Antigen 19-9 (CA 19-9)

   GI Cancer Antigen

Clinical Significance

   CA 19-9 is used as a tumor marker: to help tell the difference between cancer of the pancreas and bile ducts and other non-cancerous conditions; such as pancreatitis, to monitor a patient's response to pancreatic cancer treatment and to look for pancreatic cancer recurrence.

Specimen

   Serum

Stability

   Refrigerated (preferred) : 7 days

   Frozen : 90 days

   Ambient : 8 hours

Reference Range

   < 39 U/ml

Interpretation

   Serial monitoring of carbohydrate antigen 19-9 (CA 19-9) should begin prior to therapy to verify post-therapy decreases in CA 19-9 and to establish a baseline for evaluating possible recurrence. Single values of CA 19-9 are less informative.

   Elevated values may be caused by a variety of malignant and nonmalignant conditions including cholangiocarcinoma, pancreatic cancer, and colon cancer.

Limitation

   Carbohydrate antigen 19-9 (CA 19-9) is neither specific nor sensitive enough to be used as a cancer screen. Some individuals do not express CA 19-9. Consequently low values in these individuals are not informative regarding cancer recurrence.

   Do not interpret serum CA 19-9 levels as absolute evidence of the presence or the absence of malignant disease. Use serum CA 19-9 in conjunction with information from the clinical evaluation of the patient and other diagnostic procedures.