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As an adjunct in the assessment of pancreatic cysts, when used in conjunction with carcinoembryonic antigen, amylase, imaging studies and cytology
Carbohydrate antigen 19-9 (CA 19-9) is a modified Lewis(a) blood group antigen, which has been used as a tumor marker. Serum CA 19-9 concentrations may be elevated in patients with gastrointestinal malignancies such as cholangiocarcinoma, colon cancer, or pancreatic cancer. While serum CA 19-9 is neither sensitive nor specific for pancreatic cancer, concentrations of CA 19-9 in pancreatic cyst fluid may help determine whether a pancreatic cyst is benign.
Cystic lesions of the pancreas are of various types:
-Benign cysts:
-Inflammatory cysts (pseudocysts)
-Serous cysts (serous cystadenoma)
-Mucinous cysts:
-Premalignant (mucinous cystadenoma)
-Malignant (cystadenocarcinoma, intrapapillary mucinous neoplasia)
Pancreatic cyst fluid CA 19-9 results should be used in conjunction with imaging studies, cytology, and other cyst-fluid tumor markers, such as carcinoembryonic antigen and amylase.
An interpretive report will be provided.
Cyst fluid carbohydrate antigen 19-9 (CA19-9) concentrations less than or equal to 37 U/mL indicate a low risk for a mucinous cyst and are more consistent with serous cystadenoma or pseudocyst. The sensitivity and specificity are approximately 19% and 98%, respectively, at this concentration.
Correlation of these test results with cytology and imaging is recommended.
Carbohydrate antigen 19-9 (CA 19-9) and other tumor markers are not specific for malignancy and CA 19-9 testing has limited utility when used as the sole tumor marker test. Other tests (eg, carcinoembryonic antigen, amylase, cytology) should be performed in conjunction with CA 19-9 for assessing pancreatic cyst aspirates.
A low or negative result (<5 U/mL) may be uninformative or misleading since some individuals (Lewis nonsecretors) do not produce the CA 19-9 antigen. In such cases, a serum CA 19-9 measurement is necessary to verify that the patient is (or is not) a CA 19-9 secretor.
1. Snozek CL, Jenkins SM, Bryant SC, et al: Analysis of CEA, CA19-9 and amylase in pancreatic cyst fluid for diagnosis of pancreatic lesions. Clin Chem. 2008;54(6 Suppl S):A126-127
2. van der Waaij LA, van Dullemen HM, Porte RJ: Cyst fluid analysis in the differential diagnosis of pancreatic cystic lesions: a polled analysis. Gastrointest Endosc. 2005;62:383-389
3. Khalid A, Brugge W: ACG practice guidelines for the diagnosis and management of neoplastic pancreatic cysts. Am J Gastroenterol. 2007 Oct;102(10):2339-2349