CA 19‑9 assay values can assist in the differential diagnosis and monitoring of patients with pancreatic carcinoma (sensitivity 70‑87 %). There is no correlation between tumor mass and the CA 19‑9 assay values. However, patients with CA 19‑9 serum levels above 10000 U/mL almost always have distal metastasis.
The determination of CA 19‑9 cannot be used for the early detection of pancreatic carcinoma. In hepatobiliary carcinoma the CA 19‑9 values provide a sensitivity of 50‑75 %. The concomitant determination of CA 72‑4 and CEA is recommended in cases of gastric carcinoma. In colorectal carcinoma, determination of CEA alone is adequate; only in rare CEA‑negative cases the determination of CA 19‑9 can be useful.
As the mucin is excreted exclusively via the liver, even slight cholestasis can lead to clearly elevated CA 19‑9 serum levels in some cases. Elevated CA 19‑9 values are also found with a number of benign and inflammatory diseases of the gastrointestinal tract and the liver, as well as in cystic fibrosis.
Manufacturer’s Reagent package insert, Elecsys and cobas e analyzers CA 19-9, 2018-01, V.22, Roche Diagnostics GmbH, Sandhofer Strasse 116, D-68305 Mannheim.