Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (778 page)

Increased In

   Carcinoma of the pancreas (80%).

   Pancreatitis—concentrations are usually <75 U/mL but are much higher in pancreatic cancer.

   Hepatobiliary cancer (22–51%).

   Gastric cancer (42%).

   Colon cancer (20%) is associated with very poor prognosis.

   Noncancerous conditions that may elevate include cirrhosis, cholangitis, hepatitis, pancreatitis, and nonmalignant GI diseases.

   Can be considered as a marker of MTC dedifferentiation and diseases aggressiveness.

Decreased In

   Limitations

   Individuals with blood group antigen Le a-b- do not synthesize CA 19-9 (5–10% of population).

   No value in screening because its PPV <1%. However, levels of >1,000 U/mL have 97% PPV.

   The CA 19-9 levels in a given specimen determined with assays from different manufacturers can vary due to differences in assay methods and reagent specificity and cannot be used interchangeably. If, in the course of monitoring a patient, the assay method used is changed, additional sequential testing should be carried out to confirm baseline values.

CANCER ANTIGEN 27.29 (CA 27.29)

   Definition

   Monoclonal antibody to a glycoprotein (Muc-1) that is present on the apical surface of normal epithelial cells. Tumor marker similar to cancer antigen 15-3