This a tumour marker.
Levels may be grossly raised in pancreatic carcinoma.
However, elevated levels are also seen in colorectal carcinoma, carcinoma of the stomach, gallbladder, biliary tract and hepatoma.
Also elevated levels may also occur in conditions such as chronic pancreatitis and some liver diseases.
A review noted that (1):
- CA 19-9 serum levels have a sensitivity and specificity of 79-81% and 82-90% respectively for the diagnosis of pancreatic cancer in symptomatic patients; but are not useful as a screening marker because of low positive predictive value (0.5-0.9%)
- pre-operative CA 19-9 serum levels provide useful prognostic information as patients with normal levels (<37 U/mL) have a prolonged median survival (32-36 months) compared to patients with elevated levels (>37 U/mL) (12-15 months)
- a CA 19-9 serum level of <100 U/mL implies likely resectable disease whereas levels >100 U/mL suggest unresectablity or metastatic disease
- important limitations to CA 19-9 serum level evaluation in pancreatic cancer include poor sensitivity, false negative results in Lewis negative phenotype (5-10%) and increased false positivity in the presence of obstructive jaundice (10-60%)
- the study authors concluded:
- CA 19-9 serum levels can provide important information with regards to prognosis, overall survival, and response to chemotherapy as well as predict post-operative recurrence
- however, non-specific expression in several benign and malignant diseases, false negative results in Lewis negative genotype and an increased false positive results in the presence of obstructive jaundice severely limit the universal applicability of serum CA 19-9 levels in pancreatic cancer management
Reference:
- Ballehaninna UK, Chamberlain RS. The clinical utility of serum CA 19-9 in the diagnosis, prognosis and management of pancreatic adenocarcinoma: An evidence based appraisal. J Gastrointest Oncol. 2012 Jun;3(2):105-19.