Carbohydrate antigen 125
Also written as: CA 125 — Carbohydrate antigen 125
A tumor marker elevated in various gastrointestinal malignancies, particularly useful in monitoring treatment response and recurrence.
Full Definition
Carbohydrate antigen 125 (CA 125) is a high molecular weight glycoprotein that serves as a tumor marker in several gastrointestinal cancers, most notably ovarian cancer but also pancreatic, gastric, and colorectal malignancies. While not specific for any single cancer type, CA 125 levels can be useful for monitoring treatment response and detecting disease recurrence in conjunction with imaging and clinical assessment. Normal values are typically below 35 U/mL, though levels can be elevated in benign conditions including inflammation, liver disease, and menstruation. Serial measurements are more clinically relevant than single values.
Usage
Usage note: Always include units (U/mL) when reporting values; distinguish from other CA tumor markers.
In Context
- "CA 125 levels decreased from 485 to 89 U/mL following three cycles of chemotherapy." — Laboratory report
- "Rising CA 125 values prompted imaging evaluation for disease recurrence." — Follow-up clinic note