CA 19-9
Pronunciation: C-A nineteen-nine
Also written as: CA 19-9 — cancer antigen 19-9
A tumor marker glycoprotein commonly elevated in pancreatic and biliary tract cancers.
Full Definition
Cancer antigen 19-9 (CA 19-9) serves as the most widely used serum biomarker for pancreatic adenocarcinoma monitoring and prognostication. Normal values are typically less than 37 units per milliliter (U/mL), with elevated levels correlating with advanced disease and poor prognosis. However, CA 19-9 lacks specificity and can be elevated in benign biliary obstruction. Additionally, approximately 7% of the population cannot produce CA 19-9 due to Lewis antigen deficiency. Editorial precision is essential for proper unit notation and clinical interpretation context.
Usage
Usage note: Include space between CA and 19-9; use U/mL for units with forward slash formatting.
In Context
- "Serum CA 19-9 levels decreased significantly following neoadjuvant therapy." — Oncology follow-up note
- "Elevated CA 19-9 at 1,250 U/mL suggested advanced pancreatic malignancy." — Laboratory interpretation